0000454: FIXED: big in the ErrorFunction() (about 1E-10 in magnitude)

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Category

Severity

Reproducibility

Date Submitted

Last Update

0000454

[ALGLIB] Spec.functions

major

always

2012-05-08 20:43

2012-06-29 10:33

Reporter

exp_1

View Status

public

Assigned To

SergeyB

Priority

normal

Resolution

fixed

Status

resolved

Product Version

Summary

0000454: FIXED: big in the ErrorFunction() (about 1E-10 in magnitude)

Description

Erf function returns incorrect results. Error is about 1e-10.
Sing is lost in constant 0.288805137207594084924010.
Must be -0.288805137207594084924010.

For example, in Delphi file normaldistr.pas

Wrong code:
P := 0.288805137207594084924010+XSq*P;

Correct code:
P := -0.288805137207594084924010+XSq*P;

Files affected:
cpp\src\specialfunctions.cpp
csharp\src\specialfunctions.cs
ipython\csharp-src\specialfunctions.cs
vbnet\csharp-src\specialfunctions.cs
cpython\core\src\normaldistr.c
vb6\src\normaldistr.bas
freepascal\src\normaldistr.pas
delphi\src\normaldistr.pas

Additional Information

Proof:
See:
http://www.wolframalpha.com/input/?i=erf%284%2F10%29

Now erf(0.4) =0.42839235536425169
Must be 0.4283923550466684551036038453201724441218629285225903...
Correcting =0.42839235504666845

Programming language

All

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Issue History
Date Modified	Username	Field	Change
2012-05-08 20:43	exp_1	New Issue
2012-05-08 20:43	exp_1	Programming language	=> All
2012-05-15 10:03	SergeyB	Status	new => assigned
2012-05-15 10:03	SergeyB	Assigned To	=> SergeyB
2012-05-15 10:04	SergeyB	Target Version	=> 3.6.0
2012-06-29 10:33	SergeyB	Status	assigned => resolved
2012-06-29 10:33	SergeyB	Fixed in Version	=> 3.6.0
2012-06-29 10:33	SergeyB	Resolution	open => fixed
2012-06-29 10:33	SergeyB	Summary	Erf function returns incorrect results. Error is about 1e-10. => FIXED: big in the ErrorFunction() (about 1E-10 in magnitude)
2012-06-29 10:33	SergeyB	Description Updated

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