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[Bug math/20894] New: The strange behavior of the log function
- From: "l6979630 at hotmail dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sourceware dot org
- Date: Thu, 01 Dec 2016 10:19:02 +0000
- Subject: [Bug math/20894] New: The strange behavior of the log function
- Auto-submitted: auto-generated
https://sourceware.org/bugzilla/show_bug.cgi?id=20894
Bug ID: 20894
Summary: The strange behavior of the log function
Product: glibc
Version: 2.19
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: math
Assignee: unassigned at sourceware dot org
Reporter: l6979630 at hotmail dot com
Target Milestone: ---
I found this bug on ubuntu 14.04 with glibc 2.19 and arch linux with glibc
2.24.
#include<cstdio>
#include<cmath>
using namespace std;
double p[5];
int ans;
double yy(int x){
return log(x);
}
double cc(int x){
return p[x];
}
int main(){
p[2]=log(2);
double a = log(2)/log(2);
printf("%d\n",(int)a);
printf("%d\n",(int)(log(2)/log(2)));
printf("%d\n",(int)(yy(2)/yy(2)));
printf("%d\n",(int)(cc(2)/cc(2)));
}
Just compile this program in "g++ -match=i686 -m32 code,cpp"
Then you will got outputs like:
1
0
0
1
It is really strange.......
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