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[Bug math/14471] New: Inaccurate y0f function on x86_32
- From: "liubov.dmitrieva at gmail dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sources dot redhat dot com
- Date: Wed, 15 Aug 2012 14:13:48 +0000
- Subject: [Bug math/14471] New: Inaccurate y0f function on x86_32
- Auto-submitted: auto-generated
http://sourceware.org/bugzilla/show_bug.cgi?id=14471
Bug #: 14471
Summary: Inaccurate y0f function on x86_32
Product: glibc
Version: 2.17
Status: NEW
Severity: normal
Priority: P2
Component: math
AssignedTo: unassigned@sourceware.org
ReportedBy: liubov.dmitrieva@gmail.com
Classification: Unclassified
Test case:
// gcc main.c -std=c99 -lm -m32
#include <stdio.h>
#include <fenv.h>
#include <stdlib.h> // abs function for int argument
extern float y0f(float);
extern double y0(double);
#define i32(a) (((int*)&(a))[0])
int main() {
float a,r1,r2;
i32(a)=0x4155c70d; //argument
fesetround(FE_TONEAREST);
r1 = y0f(a); //actual result
r2 = y0(a); //actual result 2
printf("inputs: a = (0x%08x)\t%e\n", i32(a), a);
printf("actual = (0x%08x)\t%.13e\n", i32(r1), r1);
printf("expected = (0x%08x)\t%.13e\n", i32(r2), r2);
printf("error = %d ulp\n", abs(i32(r1) - i32(r2)));
return 0;
}
Result:
(core 2 for example):
-bash-4.2$ gcc main_y0f.c -lm -odo -m32
-bash-4.2$ ./do
inputs: a = (0x4155c70d) 1.336110e+01
actual = (0xb4801c51) -2.3862460807322e-07
expected = (0xb47ff7c8) -2.3838867946324e-07
error = 9353 ulp
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