How to matrix inversion For 1 Dimension with c code?

Question

hello i used gauss jordan for 1d but i didnt

i want to find 1d matrix inverse. I found determinant but i dont know inverse of this matrix

Hello my dear friends

Our matrixes:

double A[] = {6, 6 ,2, 4, 9 ,7, 4, 3 ,3};
double B[] = {6, 6 ,2, 4, 9 ,7, 4, 3 ,3};
double Final[9];

Function to calculate determinant:

int Inverse(double *A, double *C, int N){

    int n = N;
        int  i, j, k;
        float a[10][10] = { 0.0 };
        double C[9] = { 0.0 };
    float pivot = 0.0;
    float factor = 0.0;
    double sum = 0.0;  ```  variables



    for (k = 1; k <= n - 1; k++)
    {

        if (a[k][k] == 0.0)
        {

            printf("error");

        }
        else
        {
            pivot = a[k][k];
            for (j = k; j <= n + 1; j++)
                a[k][j] = a[k][j] / pivot;

            for (i = k + 1; i <= n; i++)
            {
                factor = a[i][k];

                for (j = k; j <= n + 1; j++)
                {
                    a[i][j] = a[i][j] - factor * a[k][j];
                }
            }

        }

        if (a[n][n] == 0)

            printf("error");

        else
        {

            C[n] = a[n][n + 1] / a[n][n];

            for (i = n - 1; i >= 1; i--)
            {

                sum = 0.0;

                for (j = i + 1; j <= n; j++)

                    sum = sum + a[i][j] * C[j];

                C[i] = (a[i][n + 1] - sum) / a[i][i];

            }

        }

    }

    for (i = 1; i <= n; i++)
    {

        printf("\n\tx[%1d]=%10.4f", i, C[i]);

    }

    system("PAUSE");
    return 0;

}

Although I tried very hard, I couldn't find the opposite in c programming for a 1x1 dimensional matrix. Output always generates 0. Can you help me where I could be making a mistake. Thank you.

Answer 1

It appears you are using C as an output parameter (to store the inverse); however, you also declare a local variable of the same name in the function. This causes the local variable to shadow (i.e.: hide) the output parameter; thus, changes you make to the C in the function do not affect the C the calling function sees.

To fix this issue, you need to remove the line double C[9] = {0}; from your function.