Segmentation fault when the program tries write out the results - c

Question

Greeting,
Somebody can find, why write out these program segmenation fault, when I take in the all inputs?
I don't find where is the problem, or where should be modify my code
And I would like to get the results?
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
void inMatrix(int n, double **matrix)
{
int j, i;
for (i = 0; i < n; i++)
{
for (j= 0; j < n; j++)
{
scanf("%lf", &matrix[i][j]);
}
}
}
void inVector(double *vektor, int n)
{
int k;
for (k = 0; k < n; k++)
{
scanf("%lf", &vektor[k]);
}
}
void outVector(double *vektor, int n)
{
int k;
for (k = 0; k < n; k++)
{
printf("%.8lf ", vektor[k]);
}
}
void lup(int n, double **A, double **b, int v)
{
int *Permutation = (int*)malloc(sizeof(int)*n);
int i,j;
int k;
double *max = (double*) malloc (sizeof(double)*n);
int m=0, p=0;
int tmp=0, tmp2=0;
int t=0, isSingular=0;
double largestElement=0.0;
double *helpVector = (double*) malloc (sizeof(double)*n);
double *helpVectorA = (double*) malloc (sizeof(double)*n);
double *helpVectorB = (double*) malloc (sizeof(double)*n);
// for(i=0;i<n;i++)
// {
// for(j=0;j<n;j++)
// {
// A[i][j]=D[i][j];
// }
// }
for(i=0; i<n; i++)
Permutation[i]=i;
for(m=0; m<n-1; m++)
{
for(i=m; i<n; i++)
{
max[i]=fabs(A[i][m]);
}
for(i=m; i<n; i++)
{
if(max[i]>largestElement)
{
largestElement=max[i];
p=i;
}
}
for(i=0; i<n; i++)
{
helpVectorA[i]=A[m][i];
helpVectorB[i]=A[p][i];
}
for(i=0; i<n; i++)
{
A[m][i]=helpVectorB[i];
A[p][i]=helpVectorA[i];
}
tmp=Permutation[m];
tmp2=Permutation[p];
Permutation[m]=tmp2;
Permutation[p]=tmp;
if(fabs(A[m][m])>0.00000000000000001)
{
for(i=m+1; i<n; i++)
{
A[i][m]=A[i][m]/A[m][m];
for(j=m+1; j<n; j++)
{
A[i][j]=A[i][j]-A[i][m]*A[m][j];
}
}
}
if(fabs(A[m][m])<0.00000000001)
{
printf("szingularis\n");
isSingular=1;
break;
}
for(i=0; i<n; i++) max[i]=-1;
largestElement=0.0;
p=m+1;
}
if(isSingular==0)
{
if(fabs(A[n-1][n-1])<0.00000000001)
{
printf("szingularis\n");
isSingular=1;
}
}
if(isSingular==0)
{
for(k=0; k<v;k++)
{
for(i=0; i<n; i++)
{
t=Permutation[i];
helpVector[i]=b[k][t];
}
for(i=0; i<n; i++)
{
b[i][k]=helpVector[i];
}
for(i=1; i<n; i++)
{
for(j=0; j<i; j++)
{
b[k][i]-=A[i][j]*b[k][j];
}
}
for(i=n-1; i>=0; i--)
{
for(j=i+1; j<n; j++)
{
b[k][i]-=A[i][j]*b[k][j];
}
b[k][i]=b[k][i]/A[i][i];
}
}
for(i=0; i<n; i++)
{
printf("%.8lf ", b[k][i]);
}
printf("\n");
}
}
int main()
{
int k, v,n;
int j;
double **A;
double **C;
// read dimension of matrix and value
scanf("%d", &n);
//matrix
A = (double **) calloc(n, sizeof ( double*));
// matrix to store the vectors
C = (double **) calloc(n, sizeof(double *));
while(n!=0)
{
for (k = 0; k < n; k++)
{
A[k] = (double *) calloc(n, sizeof ( double));
}
inMatrix(n, A);
scanf("%d", &v);
for(k=0;k<v;k++)
{
C[k] = (double *) calloc(n, sizeof ( double));
}
for(k=0; k<v;k++)
{
for(j=0;j<n;j++)
{
scanf("%lf", &C[k][j]);
}
}
//print out result
for(k=0;k<v;k++)
{
for(j=0;j<v;j++)
{
lup(n,A,C,v);
}
}
}
return 0;
}

Answer 1

In main, you have
/* ... */
C = (double **) calloc(n, sizeof(double *));
n elements
while(n!=0)
{
for (k = 0; k < n; k++)
{
A[k] = (double *) calloc(n, sizeof ( double));
}
inMatrix(n, A);
scanf("%d", &v);
for(k=0;k<v;k++)
v? Where did it come from? Do you perhaps mean n
Remember C was allocated space for n elements, even before v was set.
{
C[k] = (double *) calloc(n, sizeof ( double));
}
/* ... */
Your indentation and use of whitespace could improve a bit too.

Answer 2

In function lup, at line 157 (in the second "if(isSingular==0)" block) you wrote
printf("%.8lf ", b[k][i]);
this line is written in a for-loop iterating on i, while k has a leftover value from the last loop. The break condition of that loop was that k = v (the size of C, A.K.A "b" from the line of code above).
So, basically, you wrote:
printf("%.8lf", b[MaxIndexOfB+1][i];
And that's probably the stinker you're looking for.
Two notes. First, I've been .Net man for too long, so I might be missing something completely trivial here, In that case, sorry.
Second, when you want people to read your code (like when posting it for help), it's imperative to use more meaningful names, or something to improve code readability, but if you're not going to do this, at least avoid confusing stuff like passing variable named "C" into parameter named "b" if it's avoidable.

Answer 3

Checkout this tutorial. It teaches you how to find segfaults using GDB.