CODEWITHSUNDEEP
carrays
chr
chr

Reputation: 101

Merging multidimensional arrays in C

I want to "append" a vector to matrix, eg

[1 2; & (5       [1 2 5;
3 4]     6) -->   3 4 6];

trying to emulate math script. I seemingly don't understand arrays and pointers in C because when I try to do that in C I with the following code

EDIT: Posted messed up code which was redundant. When using the function mmerge, the "problem" persists.

#include <stdio.h>

//void printMatrix(const int N, const int M, double A[N][M]);

void mmerge(const int N, const double A[N][N], const double b[N], double F[N][N])
{
    for(int i = 0; i < N; i++) {
        for(int j = 0; j < N; j++) {
            F[i][j] = A[i][j];
        }
        F[i][N] = b[i];
    }
}

// Prints a two-dimensional array as a matrix
void printMatrix(const int N, const int M, double A[N][M]){
    int i, j;
    for(i=0; i<N; ++i){
        printf("|");
        for(j=0; j<M; ++j){
            printf(" % 8.4f", A[i][j]);
            if(j != M-1) printf(",");
        }
        printf(" |\n");
    }
    printf("\n");
}

int main() 
{
    const int N=2;
    double A[2][2] = {{1,2},{3,4}};
    double b[2] = {5,6};
    double F[2][3];
    mmerge(2,A,b,F);
    printMatrix(2, 3, F);
    return 0;
}

I get

|   1.0000,   2.0000,   3.0000 |
|   4.0000,   6.0000,   0.0000 |

What happens and why is it not the expected result?

Upvotes: 0

Views: 1014

Answers (3)

Rishab Tyagi
Rishab Tyagi

Reputation: 926

/Bro your code is wrong here/

void mmerge(const int N, const double A[N][N], const double b[N], double F[N][N]+1)

use double F[N][N+1]) instead of double F[N][N]+1).

Corrected code with correct output

Upvotes: 0

chr
chr

Reputation: 101

Forgot N+1

I want to "append" a vector to matrix, eg

[1 2; & (5       [1 2 5;
3 4]     6) -->   3 4 6];

trying to emulate math script. I seemingly don't understand arrays and pointers in C because when I try to do that in C I with the following code

EDIT: Posted messed up code which was redundant. When using the function mmerge, the "problem" persists.

#include <stdio.h>

//void printMatrix(const int N, const int M, double A[N][M]);

void mmerge(const int N, const double A[N][N], const double b[N], double F[N][N]+1)
{
    for(int i = 0; i < N; i++) {
        for(int j = 0; j < N; j++) {
            F[i][j] = A[i][j];
        }
        F[i][N] = b[i];
    }
}

// Prints a two-dimensional array as a matrix
void printMatrix(const int N, const int M, double A[N][M]){
    int i, j;
    for(i=0; i<N; ++i){
        printf("|");
        for(j=0; j<M; ++j){
            printf(" % 8.4f", A[i][j]);
            if(j != M-1) printf(",");
        }
        printf(" |\n");
    }
    printf("\n");
}

int main() 
{
    const int N=2;
    double A[2][2] = {{1,2},{3,4}};
    double b[2] = {5,6};
    double F[2][3];
    mmerge(2,A,b,F);
    printMatrix(2, 3, F);
    return 0;
}

Upvotes: 1

JAKE
JAKE

Reputation: 547

What does your function after double F[2][3]; do?

Also, your merging function should be like this

for(int i = 0; i < N; i++) {
    for(int j = 0; j < N; j++) {
        F[i][j] = A[i][j];
    }

}

    for(j = 0; j < N; j++) {
        F[j][M-1] = b[j];
    }

Upvotes: 0

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