For some reason, the following code doesn't work:
#include<stdio.h>
#include<stdlib.h>
#include<math.h>
/* float determinant(float *a, int n) {{{1 */
float determinant(float *a, int n)
{
float *b, det=0;
if(n<2)
return 0;
if(n==2)
det=( (*a)*(*(a+3)) - (*(a+1))*(*(a+2)));
else
{
b=malloc((n-1)*(n-1)*sizeof(float));
int i,j,k,m=0,l=0;
for(i=0;i<n;i++)
{
for(j=1;j<n;j++)
for(k=0;k<n;k++)
if(k!=i)
{
*(b + (n-1)*l + m)=
*(a + n*j+ k);
m++;
l+=m/(n-1);
m%=(n-1);
}
det+=(*(a+i))*determinant(b, n-1)*pow(-1,i);
}
free(b);
}
return det;
}
/* 1}}} */
int main()
{
float *a, det;
int n,i,j;
printf("Enter the no. of rows\n# ");
scanf("%d", &n);
printf("\n\n");
a=malloc(n*n*sizeof(float));
for(i=0;i<n;i++)
for(j=0;j<n;j++)
{
printf("Enter element (%d,%d)# ", (i+1), (j+1));
scanf("%f", (a + i*n + j));
}
det=determinant(a, n);
free(a);
printf("\n\nThe determinant is: %f\n\n", det);
return 0;
}
Any help is appreciated.
Here is the error:
*** glibc detected *** ./a.out: free(): invalid next size (fast):
0x0000000000601040 ***
======= Backtrace: =========
/lib/libc.so.6[0x2ab41ff97b23]
/lib/libc.so.6(cfree+0x8c)[0x2ab41ff9b26c]
./a.out[0x400877]
./a.out[0x40095a]
/lib/libc.so.6(__libc_start_main+0xf4)[0x2ab41ff458e4]
./a.out[0x4005e9]
======= Memory map: ========
00400000-00401000 r-xp 00000000 08:04 4014120
/home/aneeshm/work/se/pl-ass/mat/a.out
00600000-00601000 rw-p 00000000 08:04 4014120
/home/aneeshm/work/se/pl-ass/mat/a.out
00601000-00622000 rw-p 00601000 00:00 0 [heap]
2ab41fa89000-2ab41faa5000 r-xp 00000000 08:04 8880137
/lib/ld-2.5.so
2ab41faa5000-2ab41faaa000 rw-p 2ab41faa5000 00:00 0
2ab41fca4000-2ab41fca6000 rw-p 0001b000 08:04 8880137
/lib/ld-2.5.so
2ab41fca6000-2ab41fd27000 r-xp 00000000 08:04 8912908
/lib/libm-2.5.so
2ab41fd27000-2ab41ff26000 ---p 00081000 08:04 8912908
/lib/libm-2.5.so
2ab41ff26000-2ab41ff28000 rw-p 00080000 08:04 8912908
/lib/libm-2.5.so
2ab41ff28000-2ab42006f000 r-xp 00000000 08:04 8880190
/lib/libc-2.5.so
2ab42006f000-2ab42026f000 ---p 00147000 08:04 8880190
/lib/libc-2.5.so
2ab42026f000-2ab420272000 r--p 00147000 08:04 8880190
/lib/libc-2.5.so
2ab420272000-2ab420274000 rw-p 0014a000 08:04 8880190
/lib/libc-2.5.so
2ab420274000-2ab42027a000 rw-p 2ab420274000 00:00 0
2ab42027a000-2ab420287000 r-xp 00000000 08:04 8880139
/lib/libgcc_s.so.1
2ab420287000-2ab420487000 ---p 0000d000 08:04 8880139
/lib/libgcc_s.so.1
2ab420487000-2ab420488000 rw-p 0000d000 08:04 8880139
/lib/libgcc_s.so.1
2ab424000000-2ab424021000 rw-p 2ab424000000 00:00 0
2ab424021000-2ab428000000 ---p 2ab424021000 00:00 0
7fff8b00c000-7fff8b021000 rw-p 7fff8b00c000 00:00 0 [stack]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vdso]
Aborted (core dumped)
--
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