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さまざまな言語で数値計算

Only Do What Only You Can Do

指数関数 (級数展開)

級数展開(テイラー展開)で $ e^x $ を求めます.

VBScript

Option Explicit

Dim i
For i = 0 To 20
    Dim x:  x  = (i - 10) / 4.0
    '標準の指数関数
    Dim d1: d1 = Exp(x)
    '自作の指数関数
    Dim d2: d2 = myExp(x, 1, 1.0, 1.0, 1.0)
    '標準関数との差異
    WScript.StdOut.Write Right(Space(5)  & FormatNumber(x,        2, -1, 0, 0),  5) & " : "
    WScript.StdOut.Write Right(Space(13) & FormatNumber(d1,      10, -1, 0, 0), 13) & " - "
    WScript.StdOut.Write Right(Space(13) & FormatNumber(d2,      10, -1, 0, 0), 13) & " = "
    WScript.StdOut.Write Right(Space(13) & FormatNumber(d1 - d2, 10, -1, 0, 0), 13) & vbNewLine
Next

'自作の指数関数
Private Function myExp(ByVal x, ByVal n, ByVal numerator, ByVal denominator, ByVal y)
    denominator     = denominator * n
    numerator       = numerator   * x
    Dim a: a = numerator / denominator
    '十分な精度になったら処理を抜ける
    If (Abs(a) <= 0.00000000001) Then
        myExp = y
    Else
        myExp = y + myExp(x, n + 1, numerator, denominator, a)
    End If
End Function
Z:\>cscript //nologo 0504.vbs
-2.50 :  0.0820849986 -  0.0820849986 = -0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 = -0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 = -0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 = -0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 = -0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

JScript

for (var i = -10; i <= 10; i++)
{
    var x  = i / 4.0;
    // 標準の指数関数
    var d1 = Math.exp(x);
    // 自作の指数関数
    var d2 = myExp(x, 1, 1.0, 1.0, 1.0);
    // 標準関数との差異
    WScript.StdOut.Write(("     "         + x.toFixed(2)         ).slice(-5)  + " : ");
    WScript.StdOut.Write(("             " + d1.toFixed(10)       ).slice(-13) + " - ");
    WScript.StdOut.Write(("             " + d2.toFixed(10)       ).slice(-13) + " = ");
    WScript.StdOut.Write(("             " + (d1 - d2).toFixed(10)).slice(-13) + "\n" );
}

// 自作の指数関数
function myExp(x, n, numerator, denominator, y)
{
    denominator = denominator * n;
    numerator   = numerator   * x;
    var a       = numerator / denominator;
    // 十分な精度になったら処理を抜ける
    if (Math.abs(a) <= 0.00000000001)
        return y;
    else
        return y + myExp(x, ++n, numerator, denominator, a);
}
Z:\>cscript //nologo 0504.js
-2.50 :  0.0820849986 -  0.0820849986 = -0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 = -0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 = -0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 = -0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 = -0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

PowerShell

# 自作の指数関数
function myExp($x, $n, $numerator, $denominator, $y)
{
    $denominator = $denominator * $n
    $numerator   = $numerator   * $x
    $a           = $numerator / $denominator
    # 十分な精度になったら処理を抜ける
    if ([Math]::Abs($a) -le 0.00000000001)
    {
        $y
    }
    else
    {
        $y + (myExp $x ($n + 1) $numerator $denominator $a)
    }
}

foreach ($i in 0..20)
{
    $x = ($i - 10) / 4.0
    # 標準の指数関数
    $d1 = [Math]::Exp($x)
    # 自作の指数関数
    $d2 = myExp $x 1 1.0 1.0 1.0
    # 標準関数との差異
    Write-Host ([string]::format("{0,5:F2} : {1,13:F10} - {2,13:F10} = {3,13:F10}", $x, $d1, $d2, $d1 - $d2))
}
Z:\>powershell -file 0504.ps1
-2.50 :  0.0820849986 -  0.0820849986 =  0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 =  0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 =  0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 =  0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 =  0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

Perl

# 自作の指数関数
sub myExp
{
    my ($x, $n, $numerator, $denominator, $y) = @_;

    $denominator = $denominator * $n;
    $numerator   = $numerator   * $x;
    $a           = $numerator / $denominator;
    # 十分な精度になったら処理を抜ける
    if (abs($a) <= 0.00000000001)
    {
        $y;
    }
    else
    {
        $y + myExp($x, ++$n, $numerator, $denominator, $a);
    }
}

for $i (0..20)
{
    $x  = ($i - 10) / 4.0;
    # 標準の指数関数
    $d1 = exp($x);
    # 自作の指数関数
    $d2 = myExp($x, 1, 1.0, 1.0, 1.0);
    # 標準関数との差異
    printf("%5.2f : %13.10f - %13.10f = %13.10f\n", $x, $d1, $d2, $d1 - $d2);
}
Z:\>perl 0504.pl
-2.50 :  0.0820849986 -  0.0820849986 = -0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 = -0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 = -0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 = -0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 = -0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

PHP

<?php
# 自作の指数関数
function myExp($x, $n, $numerator, $denominator, $y)
{
    $denominator = $denominator * $n;
    $numerator   = $numerator   * $x;
    $a           = $numerator / $denominator;
    # 十分な精度になったら処理を抜ける
    if (abs($a) <= 0.00000000001)
        return $y;
    else
        return $y + myExp($x, ++$n, $numerator, $denominator, $a);
}

foreach (range(0, 20) as $i)
{
    $x  = ($i - 10) / 4.0;
    # 標準の指数関数
    $d1 = exp($x);
    # 自作の指数関数
    $d2 = myExp($x, 1, 1.0, 1.0, 1.0);
    # 標準関数との差異
    printf("%5.2f : %13.10f - %13.10f = %13.10f\n", $x, $d1, $d2, $d1 - $d2);
}
?>
Z:\>php 0504.php
-2.50 :  0.0820849986 -  0.0820849986 = -0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 = -0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 = -0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 = -0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 = -0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

Python

# coding: Shift_JIS

import math
 
# 自作の指数関数
def myExp(x, n, numerator, denominator, y):
    denominator = denominator * n
    numerator   = numerator   * x
    a           = numerator / denominator
    # 十分な精度になったら処理を抜ける
    if (abs(a) <= 0.00000000001):
        return y
    else:
        return y + myExp(x, n + 1, numerator, denominator, a)

for i in range(0, 21):
    x  = (i - 10) / 4.0
    # 標準の指数関数
    d1 = math.exp(x)
    # 自作の指数関数
    d2 = myExp(x, 1, 1.0, 1.0, 1.0)
    # 標準関数との差異
    print "%5.2f : %13.10f - %13.10f = %13.10f" % (x, d1, d2, d1 - d2)
Z:\>python 0504.py
-2.50 :  0.0820849986 -  0.0820849986 = -0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 = -0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 = -0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 = -0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 = -0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

Ruby

# 自作の指数関数
def myExp(x, n, numerator, denominator, y)
    denominator = denominator * n
    numerator   = numerator   * x
    a           = numerator / denominator;
    # 十分な精度になったら処理を抜ける
    if (a.abs <= 0.00000000001)
        y
    else
        y + myExp(x, n + 1, numerator, denominator, a)
    end
end

(0..20).each do |i|
    x  = (i - 10) / 4.0
    # 標準の指数関数
    d1 = Math.exp(x)
    # 自作の指数関数
    d2 = myExp(x, 1, 1.0, 1.0, 1.0)
    # 標準関数との差異
    printf("%5.2f : %13.10f - %13.10f = %13.10f\n", x, d1, d2, d1 - d2)
end
Z:\>ruby 0504.rb
-2.50 :  0.0820849986 -  0.0820849986 = -0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 = -0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 = -0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 = -0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 = -0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

Groovy

Pascal

Program Pas0504(arg);
{$MODE delphi}

uses
    SysUtils, Math;

// 自作の指数関数
function myExp(x:Double; n:Integer; numerator:Double; denominator:Double; y:Double):Double;
var
    a: Double;
begin
    denominator := denominator * n;
    numerator   := numerator   * x;
    a           := numerator / denominator;
    // 十分な精度になったら処理を抜ける
    if (Abs(a) <= 0.00000000001) then
        result := y
    else
        result := y + myExp(x, n + 1, numerator, denominator, a);
end;

var
    i:  Integer;
    x:  Double;
    d1: Double;
    d2: Double;
begin
    for i := 0 to 20 do
    begin
        x  := (i - 10) / 4.0;
        // 標準の指数関数
        d1 := Exp(x);
        // 自作の指数関数
        d2 := myExp(x, 1, 1.0, 1.0, 1.0);
        // 標準関数との差異
        writeln(format('%5.2f : %13.10f - %13.10f = %13.10f', [x, d1, d2, d1 - d2]));
    end;
end.
Z:\>fpc Pas0504.pp -v0
Free Pascal Compiler version 2.6.2 [2013/02/12] for i386
Copyright (c) 1993-2012 by Florian Klaempfl and others

Z:\>Pas0504
-2.50 :  0.0820849986 -  0.0820849986 =  0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 =  0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 =  0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 =  0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 =  0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

Ada

VB.NET

Module VB0504
    Public Sub Main()
        For i As Integer = 0 To 20
            Dim x As Double  = (i - 10) / 4.0
            '標準の指数関数
            Dim d1 As Double = Math.Exp(x)
            '自作の指数関数
            Dim d2 As Double = myExp(x, 1, 1.0, 1.0, 1.0)
            '標準関数との差異
            Console.WriteLine(String.Format("{0,5:F2} : {1,13:F10} - {2,13:F10} = {3,13:F10}", x, d1, d2, d1 - d2))
        Next
    End Sub

    '自作の指数関数
    Private Function myExp(ByVal x As Double, ByVal n As Integer, ByVal numerator As Double, ByVal denominator As Double, ByVal y As Double) As Double
        denominator     = denominator * n
        numerator       = numerator   * x
        Dim a As Double = numerator / denominator
        '十分な精度になったら処理を抜ける
        If (Math.Abs(a) <= 0.00000000001) Then
            Return y
        Else
            Return y + myExp(x, n + 1, numerator, denominator, a)
        End If
    End Function
End Module
Z:\>vbc -nologo VB0504.vb

Z:\>VB0504
-2.50 :  0.0820849986 -  0.0820849986 =  0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 =  0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 =  0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 =  0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 =  0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

C#

using System;

public class CS0504
{
    public static void Main()
    {
        for (int i = -10; i <= 10; i++)
        {
            double x  = i / 4.0;
            // 標準の指数関数
            double d1 = Math.Exp(x);
            // 自作の指数関数
            double d2 = myExp(x, 1, 1.0, 1.0, 1.0);
            // 標準関数との差異
            Console.WriteLine(string.Format("{0,5:F2} : {1,13:F10} - {2,13:F10} = {3,13:F10}", x, d1, d2, d1 - d2));
        }
    }

    // 自作の指数関数
    private static double myExp(double x, int n, double numerator, double denominator, double y)
    {
        denominator = denominator * n;
        numerator   = numerator   * x;
        double a    = numerator / denominator;
        // 十分な精度になったら処理を抜ける
        if (Math.Abs(a) <= 0.00000000001)
            return y;
        else
            return y + myExp(x, ++n, numerator, denominator, a);
    }
}
Z:\>csc -nologo CS0504.cs

Z:\>CS0504
-2.50 :  0.0820849986 -  0.0820849986 =  0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 =  0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 =  0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 =  0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 =  0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

Java

public class Java0504 {
    public static void main(String []args) {
        for (int i = -10; i <= 10; i++) {
            double x  = i / 4.0;
            // 標準の指数関数
            double d1 = Math.exp(x);
            // 自作の指数関数
            double d2 = myExp(x, 1, 1.0, 1.0, 1.0);
            // 標準関数との差異
            System.out.println(String.format("%5.2f : %13.10f - %13.10f = %13.10f", x, d1, d2, d1 - d2));
        }
    }

    // 自作の指数関数
    private static double myExp(double x, int n, double numerator, double denominator, double y) {
        denominator = denominator * n;
        numerator   = numerator   * x;
        double a    = numerator / denominator;
        // 十分な精度になったら処理を抜ける
        if (Math.abs(a) <= 0.00000000001)
            return y;
        else
            return y + myExp(x, ++n, numerator, denominator, a);
    }
}
Z:\>javac Java0504.java

Z:\>java Java0504
-2.50 :  0.0820849986 -  0.0820849986 = -0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 = -0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 = -0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 = -0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 = -0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

C++

#include <iostream>
#include <iomanip>
#include <math>
using namespace std;

double myExp(double x, int n, double numerator, double denominator, double y);

int main()
{
    for (int i = -10; i <= 10; i++)
    {
        double x  = i / 4.0;
        // 標準の指数関数
        double d1 = exp(x);
        // 自作の指数関数
        double d2 = myExp(x, 1, 1.0, 1.0, 1.0);
        // 標準関数との差異
        cout << setw(5)  << fixed << setprecision(2)  << x  << ":";
        cout << setw(14) << fixed << setprecision(10) << d1 << " - ";
        cout << setw(14) << fixed << setprecision(10) << d2 << " = ";
        cout << setw(14) << fixed << setprecision(10) << d1 - d2 << endl;
    }
    return 0;
}

// 自作の指数関数
double myExp(double x, int n, double numerator, double denominator, double y)
{
    denominator = denominator * n;
    numerator   = numerator   * x;
    double a    = numerator / denominator;
    // 十分な精度になったら処理を抜ける
    if (fabs(a) <= 0.00000000001)
        return y;
    else
        return y + myExp(x, ++n, numerator, denominator, a);
}
Z:\>bcc32 CP0504.cpp
Borland C++ 5.5.1 for Win32 Copyright (c) 1993, 2000 Borland
CP0504.cpp:
Turbo Incremental Link 5.00 Copyright (c) 1997, 2000 Borland

Z:\>CP0504
-2.50:  0.0820849986 -   0.0820849986 =   0.0000000000
-2.25:  0.1053992246 -   0.1053992246 =   0.0000000000
-2.00:  0.1353352832 -   0.1353352832 =   0.0000000000
-1.75:  0.1737739435 -   0.1737739435 =   0.0000000000
-1.50:  0.2231301601 -   0.2231301601 =   0.0000000000
-1.25:  0.2865047969 -   0.2865047969 =   0.0000000000
-1.00:  0.3678794412 -   0.3678794412 =   0.0000000000
-0.75:  0.4723665527 -   0.4723665527 =   0.0000000000
-0.50:  0.6065306597 -   0.6065306597 =   0.0000000000
-0.25:  0.7788007831 -   0.7788007831 =   0.0000000000
 0.00:  1.0000000000 -   1.0000000000 =   0.0000000000
 0.25:  1.2840254167 -   1.2840254167 =   0.0000000000
 0.50:  1.6487212707 -   1.6487212707 =   0.0000000000
 0.75:  2.1170000166 -   2.1170000166 =   0.0000000000
 1.00:  2.7182818285 -   2.7182818285 =   0.0000000000
 1.25:  3.4903429575 -   3.4903429575 =   0.0000000000
 1.50:  4.4816890703 -   4.4816890703 =  -0.0000000000
 1.75:  5.7546026760 -   5.7546026760 =   0.0000000000
 2.00:  7.3890560989 -   7.3890560989 =   0.0000000000
 2.25:  9.4877358364 -   9.4877358364 =   0.0000000000
 2.50: 12.1824939607 -  12.1824939607 =  -0.0000000000

Objective-C

#import <Foundation/Foundation.h>

double myExp(double x, int n, double numerator, double denominator, double y);

int main()
{
    int i;
    for (i = -10; i <= 10; i++)
    {
        double x   = i / 4.0;
        // 標準の指数関数
        double d1  = exp(x);
        // 自作の指数関数
        double d2  = myExp(x, 1, 1.0, 1.0, 1.0);
        // 標準関数との差異
        printf("%+04.2f : %+014.10f - %+014.10f = %+13.10f\n", x, d1, d2, d1 - d2);
    }
    return 0;
}

// 自作の指数関数
double myExp(double x, int n, double numerator, double denominator, double y)
{
    denominator = denominator * n;
    numerator   = numerator   * x;
    double a    = numerator / denominator;
    // 十分な精度になったら処理を抜ける
    if (fabs(a) <= 0.00000000001)
        return y;
    else
        return y + myExp(x, ++n, numerator, denominator, a);
}
Compiling the source code....
$gcc `gnustep-config --objc-flags` -L/usr/GNUstep/System/Library/Libraries -lgnustep-base main.m -o demo -lm -pthread -lgmpxx -lreadline 2>&1

Executing the program....
$demo 
-2.50 : +00.0820849986 - +00.0820849986 = -0.0000000000
-2.25 : +00.1053992246 - +00.1053992246 = +0.0000000000
-2.00 : +00.1353352832 - +00.1353352832 = -0.0000000000
-1.75 : +00.1737739435 - +00.1737739434 = +0.0000000000
-1.50 : +00.2231301601 - +00.2231301602 = -0.0000000000
-1.25 : +00.2865047969 - +00.2865047969 = +0.0000000000
-1.00 : +00.3678794412 - +00.3678794412 = -0.0000000000
-0.75 : +00.4723665527 - +00.4723665527 = -0.0000000000
-0.50 : +00.6065306597 - +00.6065306597 = +0.0000000000
-0.25 : +00.7788007831 - +00.7788007831 = +0.0000000000
+0.00 : +01.0000000000 - +01.0000000000 = +0.0000000000
+0.25 : +01.2840254167 - +01.2840254167 = +0.0000000000
+0.50 : +01.6487212707 - +01.6487212707 = +0.0000000000
+0.75 : +02.1170000166 - +02.1170000166 = +0.0000000000
+1.00 : +02.7182818285 - +02.7182818285 = +0.0000000000
+1.25 : +03.4903429575 - +03.4903429575 = +0.0000000000
+1.50 : +04.4816890703 - +04.4816890703 = +0.0000000000
+1.75 : +05.7546026760 - +05.7546026760 = +0.0000000000
+2.00 : +07.3890560989 - +07.3890560989 = +0.0000000000
+2.25 : +09.4877358364 - +09.4877358364 = +0.0000000000
+2.50 : +12.1824939607 - +12.1824939607 = +0.0000000000

D

Go

Scala

対話型実行環境を起動

Z:\>scala
Welcome to Scala version 2.10.2 (Java HotSpot(TM) Client VM, Java 1.7.0_21).
Type in expressions to have them evaluated.
Type :help for more information.

級数展開(テイラー展開)で ex を求める

// 自作の指数関数
def myExp(x:Double, n:Int, numerator:Double, denominator:Double, y:Double):Double = {
    val denom = denominator * n
    val num   = numerator   * x
    val a     = num / denom
    // 十分な精度になったら処理を抜ける
    if (Math.abs(a) <= 0.00000000001)
        y
    else
        y + myExp(x, n + 1, num, denom, a)
}
(0 to 20).
    map(n => (n - 10) / 4.0).
    foreach { x =>
        // 標準の指数関数
        val d1 = Math.exp(x)
        // 自作の指数関数
        val d2 = myExp(x, 1, 1.0, 1.0, 1.0)
        // 標準関数との差異
        System.out.println("%5.2f : %13.10f - %13.10f = %13.10f".format(x, d1, d2, d1 - d2));
    }
-2.50 :  0.0820849986 -  0.0820849986 = -0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 = -0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 = -0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 = -0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 = -0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

終了

scala> :quit

F#

対話型実行環境を起動

Z:\>fsi
Microsoft (R) F# 2.0 Interactive build 4.0.40219.1
Copyright (c) Microsoft Corporation. All Rights Reserved.

For help type #help;;

級数展開(テイラー展開)で ex を求める

// 自作の指数関数
let rec myExp (x:double) (n:int) (numerator:double) (denominator:double) (y:double):double =
    let denom = denominator * (double n)
    let num   = numerator   * x
    let a     = num / denom
    // 十分な精度になったら処理を抜ける
    if abs(a) <= 0.00000000001 then
        y
    else
        y + (myExp x (n + 1) num denom a)
[0..20]
|> List.map (fun n -> (double (n - 10)) / 4.0)
|> List.iter
    (fun x -> 
        // 標準の指数関数
        let d1 = System.Math.Exp(x)
        // 自作の指数関数
        let d2 = (myExp x 1 1.0 1.0 1.0)
        // 標準関数との差異
        printfn "%5.2f : %13.10f - %13.10f = %13.10f" x d1 d2 (d1 - d2)
    )
-2.50 :  0.0820849986 -  0.0820849986 =  0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 =  0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 =  0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 =  0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 =  0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000
val it : unit = ()

終了

> #quit;;

Clojure

対話型実行環境を起動

Z:\>java -cp C:\ProgramFiles\clojure-1.5.1\clojure-1.5.1.jar clojure.main
Clojure 1.5.1

級数展開(テイラー展開)で ex を求める

;自作の指数関数
(defn myExp [x n numerator denominator y]
    (def denom (* denominator n))
    (def nume  (* numerator x))
    (def a     (/ nume denom))
    ;十分な精度になったら処理を抜ける
    (if (<= (. Math abs a) 0.00000000001)
        y
        (+ y (myExp x (+ n 1) nume denom a))))
(doseq
    [x  (map #(/ (- % 10) 4.0)
        (range 0 21))]
    (do
        ;標準の指数関数
        (def d1 (. Math exp x))
        ;自作の指数関数
        (def d2 (myExp x 1 1.0 1.0 1.0))
        ;標準関数との差異
        (println (format "%5.2f : %13.10f - %13.10f = %13.10f" x d1 d2 (- d1 d2)))))
-2.50 :  0.0820849986 -  0.0820849986 = -0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 = -0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 = -0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 = -0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 = -0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000
nil

終了

user=> (. System exit 0)

Haskell

対話型実行環境を起動

Z:\>ghci
GHCi, version 7.6.3: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.

級数展開(テイラー展開)で ex を求める

-- 自作の指数関数
myExp::Double->Int->Double->Double->Double->Double
myExp x n numerator denominator y =
let
    denom = denominator * (fromIntegral n)
    num   = numerator   * x
    a     = num / denom
in 
    -- 十分な精度になったら処理を抜ける
    if abs(a) <= 0.00000000001 then
        y
    else
        y + (myExp x (n + 1) num denom a)
import Text.Printf
import Control.Monad

forM_ (
    map (\n -> (fromIntegral (n - 10)) / 4.0) $ 
    [0..20::Int]
) $ \x -> do
    -- 標準の指数関数
    let d1 = exp(x)
    -- 自作の指数関数
    let d2 = (myExp x 1 1.0 1.0 1.0)
    -- 標準関数との差異
    printf "%5.2f : %13.10f - %13.10f = %13.10f\n" x d1 d2 (d1- d2)
-2.50 :  0.0820849986 -  0.0820849986 = -0.0000000000
-2.25 :  0.1053992246 -  0.1053992246 =  0.0000000000
-2.00 :  0.1353352832 -  0.1353352832 = -0.0000000000
-1.75 :  0.1737739435 -  0.1737739434 =  0.0000000000
-1.50 :  0.2231301601 -  0.2231301602 = -0.0000000000
-1.25 :  0.2865047969 -  0.2865047969 =  0.0000000000
-1.00 :  0.3678794412 -  0.3678794412 = -0.0000000000
-0.75 :  0.4723665527 -  0.4723665527 = -0.0000000000
-0.50 :  0.6065306597 -  0.6065306597 =  0.0000000000
-0.25 :  0.7788007831 -  0.7788007831 =  0.0000000000
 0.00 :  1.0000000000 -  1.0000000000 =  0.0000000000
 0.25 :  1.2840254167 -  1.2840254167 =  0.0000000000
 0.50 :  1.6487212707 -  1.6487212707 =  0.0000000000
 0.75 :  2.1170000166 -  2.1170000166 =  0.0000000000
 1.00 :  2.7182818285 -  2.7182818285 =  0.0000000000
 1.25 :  3.4903429575 -  3.4903429575 =  0.0000000000
 1.50 :  4.4816890703 -  4.4816890703 =  0.0000000000
 1.75 :  5.7546026760 -  5.7546026760 =  0.0000000000
 2.00 :  7.3890560989 -  7.3890560989 =  0.0000000000
 2.25 :  9.4877358364 -  9.4877358364 =  0.0000000000
 2.50 : 12.1824939607 - 12.1824939607 =  0.0000000000

終了

Prelude> :quit
Leaving GHCi.
inserted by FC2 system