c - array by malloc on function lu decomposition -

im trying lu decomposition using nxn matrix typed scanf having errors on using nxn matrix gauss function know ways use array malloc on function. way use matrix[x][y] on gauss fucntion point

#include <stdio.h>  #include <stdlib.h> #pragma warning(disable:4996)  void gauss(int n,double **matrix,double **l,double **u,double **ans);  int main(void)  {      int i, n;//     int x, y;//line x,row y     double **matrix; //define matrix[x][y]     double **l;     double **u;     double **ans;      printf("nxn matrix type n.\n");      scanf("%d", &n);        matrix = malloc(sizeof(float *) * n); // int* number x primary structure     if (matrix == null){ printf("malloc failed\n"); exit(1); }     (i = 0; i<n; i++)     {         matrix[i] = malloc(sizeof(float) * n);         if (matrix[i] == null){ printf("malloc failed\n"); exit(1); }     } //build matrix[x][y(size of x)] structure      l = malloc(sizeof(float *) * n); // int* number x primary structure     if (l == null){ printf("malloc failed\n"); exit(1); }     (i = 0; i<n; i++)     {         l[i] = malloc(sizeof(float) * n);         if (l[i] == null){ printf("malloc failed\n"); exit(1); }     } //build l[x][y(size of x)] structure      u = malloc(sizeof(float *) * n); // int* number x primary structure    if (u == null){ printf("malloc failed\n"); exit(1); }    (i = 0; i<n; i++)    {        u[i] = malloc(sizeof(float) * n);        if (u[i] == null){ printf("malloc failed\n"); exit(1); }     } //build u[x][y(size of x)] structure     ans = malloc(sizeof(float *) * n); // int* number x primary structure    if (ans == null){ printf("malloc failed\n"); exit(1); }    (i = 0; i<n; i++)    {        ans[i] = malloc(sizeof(float) * n);        if (ans[i] == null){ printf("malloc failed\n"); exit(1); }     } //build ans[x][y(size of x)] structure      printf("type number of matrix \n");     (x = 0; x < n; x++){         (y = 0; y < n; y++){             printf("line %d  x%d number : ", x + 1, y + 1);             scanf("%lf", &matrix[x][y]);         }     } /* (x = 0; x < n; x++){     (y = 0; y < n; y++){         printf("line %d  x%d number : %.2lf \n", x + 1, y + 1,matrix[x][y]);      } } */ gauss(n,matrix,l,u,ans);  /*  (i = 0; i<n; i++) {     free(matrix[i]); } free(matrix);//free matrix  (i = 0; i<n; i++) {    free(l[i]); } free(l);//free l  (i = 0; i<n; i++) { free(u[i]); } free(u);//free u */  return 0;  }  void gauss(int n,double **matrix,double **l,double **u,double **ans){ int x,y; for(x=0;x<=n;x++){     if(matrix[x][0]!=0){         for(y=0;y<=n;y++){             matrix[x][y]=matrix[x][y]/matrix[x][0];             l[x][0]=matrix[x][0];         }     } } } 

1. you allocate memory float matrix, use double, since sizes of float , double different got errors.

2. the correct way go through matrix rows , colums this

   for(x=0; x<n; x++){     ... } 

   but wrote

   for(x=0;x<=n;x++){     .... } 

   so tried access non-existing row index n (but last row has index n-1).

corrected code:

#include <stdio.h>  #include <stdlib.h>  void gauss(int n, float **matrix, float **l, float **u, float **ans);  int main(void) {      int i, n;//     int x, y;//line x,row y     float **matrix; //define matrix[x][y]     float **l;     float **u;     float **ans;      printf("nxn matrix type n.\n");      scanf("%d", &n);      matrix = malloc(sizeof(float *) * n); // int* number x primary structure     if (matrix == null){ printf("malloc failed\n"); exit(1); }     (i = 0; i<n; i++)     {         matrix[i] = malloc(sizeof(float) * n);         if (matrix[i] == null){ printf("malloc failed\n"); exit(1); }     } //build matrix[x][y(size of x)] structure      l = malloc(sizeof(float *) * n); // int* number x primary structure     if (l == null){ printf("malloc failed\n"); exit(1); }     (i = 0; i<n; i++)     {         l[i] = malloc(sizeof(float) * n);         if (l[i] == null){ printf("malloc failed\n"); exit(1); }     } //build l[x][y(size of x)] structure      u = malloc(sizeof(float *) * n); // int* number x primary structure    if (u == null){ printf("malloc failed\n"); exit(1); }    (i = 0; i<n; i++)    {        u[i] = malloc(sizeof(float) * n);        if (u[i] == null){ printf("malloc failed\n"); exit(1); }     } //build u[x][y(size of x)] structure     ans = malloc(sizeof(float *) * n); // int* number x primary structure    if (ans == null){ printf("malloc failed\n"); exit(1); }    (i = 0; i<n; i++)    {        ans[i] = malloc(sizeof(float) * n);        if (ans[i] == null){ printf("malloc failed\n"); exit(1); }     } //build ans[x][y(size of x)] structure      printf("type number of matrix \n");     (x = 0; x < n; x++){         (y = 0; y < n; y++){             printf("line %d  x%d number : ", x + 1, y + 1);             scanf("%f", &matrix[x][y]);         }     }      gauss(n,matrix,l,u,ans);      return 0; }  void gauss(int n, float **matrix, float **l, float **u, float **ans) {     int x,y;     for(x=0;x<n;x++){         if(matrix[x][0]!=0){             for(y=0;y<n;y++){                 matrix[x][y]=matrix[x][y]/matrix[x][0];                 l[x][0]=matrix[x][0];             }         }     } }