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 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.