c - Unable to find determinant using partial pivoting -


whats problem. executes doesnt show correct answer. gets compiled well. i've used calling function in many places. assumed matrix square , give input througgh terminal. ex=3 random 3x3 matrix value seems incorrect

#include<stdio.h> #include<math.h> #include<stdlib.h>  void row(int r1,int r2,int n,float a[n][n]){ int c; float temp[n][n]; for(c=0;c<n;c++){ temp[r1][c]=a[r1][c]; a[r1][c]=a[r2][c]; a[r2][c]=temp[r1][c]; } }  void maximum(int i, int n,float a[n][n]){ int j; float max=fabs(a[i][i]); for(j=i+1;j<n;j++){     if(fabs(a[j][i])>max){         max=fabs(a[j][i]);         row(i,j,n,a);     } } }  void op(int k, int n,float a[n][n]){ int i,j; float f;f for(i=1;i<n-1-k;i++){      f=-(a[k+i][k]/a[k][k]);     for(j=0;j<n-1-k;j++){            a[k+i][k+j]=a[k+i][k+j]+f*(a[k][k+j]);     } } }     int main(){ int i,j,n; printf("enter order of matrix:"); scanf("%d",&n); float a[n][n]; for(i=0;i<n;i++){     for(j=0;j<n;j++)     scanf("%f",&a[i][j]);     }  float det=1; for(i=0;i<n-1;i++){     maximum(i,n,a);     op(i,n,a);         det*=a[i][i];     } det*=a[n-1][n-1]; printf("%f\n",det); return 0; }

you reading uninitialized values

for(j=i+1;j<n;j++){     if(fabs(a[j][i])>max){         max=fabs(a[j][i]);         row(i,j,n,a);     } }

should be

for(j=i+1;j<n;j++){     if(fabs(a[i][j])>max){         max=fabs(a[i][j]);         row(i,j,n,a);     } }

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