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

Platform

Status

resolved

Projection

none

OS Version

ETA

none

Fixed in Version

3.6.0

Product Version

Target Version

3.6.0

Product Build

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

Steps To Reproduce

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

Attached Files

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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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