Re: [Mingw-msys] pow(5,2)=24 ?????!!!!!

[John Nolan <jpnolan@xxxxxxxxxxxx>]

Oops, I meant 24.9999... being rounded to 24. John

John Nolan <jpnolan@xxxxxxxxxxxx>

John Nolan <jpnolan@xxxxxxxxxxxx>
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09/07/2007 04:16 PM

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Subject	Re: [Mingw-msys] pow(5,2)=24 ?????!!!!!

The definition of pow( ) takes doubles for both arguments. Try it with double arguments and double result. Might also have rounding issues with the answer, e.g. 14.9999999... being truncated to 24. John

...........................................................................

John P. Nolan
Math/Stat Department
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American University
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...........................................................................

"Michael Chen" <vancouver.michael@xxxxxxxxx>

"Michael Chen" <vancouver.michael@xxxxxxxxx>
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09/07/2007 03:56 PM

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Subject	[Mingw-msys] pow(5,2)=24 ?????!!!!!

Hi, there,

I spent several hours and still get pow(5,2)=24 at the last line of
the code, please help!

Environment:
Windows XP
gcc.exe (GCC) 3.4.2 (mingw-special)

compile command:
gcc -g -Wall -lm spclen.c

Thanks for your help!

Michael Chen

------------------------------------------------------
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

int main()
{

 double s=0;
 int Tl=0,Ti=0;

 s=0;Tl=0;Ti=0;
 s=combinationformula(5,2,intexy11,&Tl,&Ti);
 printf("%f\t%d\t%d\n",s,Tl,Ti);


}


double combinationformula(int l, int  d, double (*f)(int, double *),
int *Tl,int *Ti)
{
 int i,j;
 int k1norm;
 int sign;
 int *I;
 int *idx;
 double s=0;
 double cho=0.0;

 *Ti=0;
 idx = idxtree(l,d,Tl);

....

}

int *idxtree(int L, int D, int *T)
{
 int i,j;
 int s;//length
 int tr;//total of a row

 int *p;//point to the full tree
 int *r;//point to the reduced tree
 int *f;//point to the flags

 *T=0;//total of multi index

 s = (int)pow(L,D); // wrong here, when L=5 D=2, I got 24!!!


...
}

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