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I'm writing an algorithm to divide a matrix into 4 submatrices(equipartitions). Size of the whole matrix is always multiplier of 4 as being shown in the added image. If you watch out, I'm trying to access elements like 1D element instead of 2D. I can't figure out the mistake at calculation part.

enter image description here

#include <stdio.h>

/* Soner Akar - Algoritmayı alırsanız lütfen benden aldığınızı belirtin. */

enum { /*BLKSZ = 4*/  NBLOCKS = 4, SIZE = 16, BLKSZ = SIZE / NBLOCKS  } ;

void get_slice( int arr[400], int slice[100], int sliceSize, int i, int j );
void get_slice( int arr[400], int slice[100], int sliceSize, int i, int j )
{
    int k = 0;
    int l = 0;
    for( k = 0 ; k < sliceSize / 2 ; ++k ) { // calculation part
        for (l = 0; l < sliceSize / 2; ++l) {
            slice[l + k * sliceSize / 2] = arr[(l + j) + (k + i) * (sliceSize / 2)];
            printf("slice[%d][%d] -> %d ", k, l, slice[l + k * (sliceSize / 2)]);
        }
        printf("\n");
    }
    printf("\n");
}

int main() {
    int matrix[SIZE] ;
    int block[BLKSZ];

    int j = 0;
    int i = 0;
    for (j = 0; j < SIZE; ++j) {
        matrix[j] = 1 + j;
    }

    for (i = 0; i < BLKSZ; ++i) {
        for (j = 0; j < BLKSZ; ++j) {
            printf("matrix[%d][%d] -> %d ", i, j, matrix[j + i * BLKSZ]);
        }
        printf("\n");
    }
    printf("\n");
    printf("\n");


    for( int i = 0 ; i < NBLOCKS ; ++i ) // get all blocks (invariant: NBLOCKS == 4)
        get_slice( matrix, block, SIZE / NBLOCKS ,BLKSZ*i/2, BLKSZ*i%2 ) ;
    return 0;
}

Output:

matrix[0][0] -> 1 matrix[0][1] -> 2 matrix[0][2] -> 3 matrix[0][3] -> 4
matrix[1][0] -> 5 matrix[1][1] -> 6 matrix[1][2] -> 7 matrix[1][3] -> 8
matrix[2][0] -> 9 matrix[2][1] -> 10 matrix[2][2] -> 11 matrix[2][3] -> 12
matrix[3][0] -> 13 matrix[3][1] -> 14 matrix[3][2] -> 15 matrix[3][3] -> 16


slice[0][0] -> 1 slice[0][1] -> 2
slice[1][0] -> 3 slice[1][1] -> 4

slice[0][0] -> 5 slice[0][1] -> 6
slice[1][0] -> 7 slice[1][1] -> 8

slice[0][0] -> 9 slice[0][1] -> 10
slice[1][0] -> 11 slice[1][1] -> 12

slice[0][0] -> 13 slice[0][1] -> 14
slice[1][0] -> 15 slice[1][1] -> 16


Process finished with exit code 0

Expected output:

slice[0][0] -> 1 slice[0][1] -> 2
slice[1][0] -> 5 slice[1][1] -> 6

slice[0][0] -> 3 slice[0][1] -> 4
slice[1][0] -> 7 slice[1][1] -> 8

slice[0][0] -> 9 slice[0][1] -> 10
slice[1][0] -> 13 slice[1][1] -> 14

slice[0][0] -> 11 slice[0][1] -> 12
slice[1][0] -> 15 slice[1][1] -> 16
Soner from The Ottoman Empire
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1 Answers1

1

You should define two variable for get_slice function because of arr column size and slice column size is different. And you can define a print function for slice to adjust readibility.

#include <stdio.h>
#include <math.h>

/* Soner Akar - Algoritmayı alırsanız lütfen benden aldığınızı belirtin. */

enum { /*BLKSZ = 4*/  NBLOCKS = 4, SIZE = 64  } ;

void get_slice( int arr[400], int slice[100], int arrSize, int sliceSize, int i, int j )
{
    int k = 0;
    int l = 0;
    int spliceColumnSize = sqrt(sliceSize);
    int arrayColumnSize = sqrt(arrSize);
    for( k = 0 ; k < spliceColumnSize ; ++k ) { // calculation part
        for (l = 0; l < spliceColumnSize; ++l) {
            slice[l + (k * (spliceColumnSize))] = arr[(i+k)*arrayColumnSize+j+l];
        }
    }
}
void printSlice(int arr[], int sliceSize)
{
    int size = sqrt(sliceSize);
    for(int i=0;i<size;++i){
        for(int j=0;j<size;++j)
        {
            printf("arr[%d][%d]:%2d, ",i,j,arr[i*(size)+j]);
        }
        printf("\n");
    }
}

int main() {
    int matrix[SIZE] ;
    int block[SIZE];

    int j = 0;
    int i = 0;
    for (j = 0; j < SIZE; ++j) {
        matrix[j] = 1 + j;
    }

    int matrixColumnSize = sqrt(SIZE);
    for (i = 0; i < matrixColumnSize; ++i) {
        for (j = 0; j < matrixColumnSize; ++j) {
            printf("matrix[%d][%d] -> %2d ", i, j, matrix[j + i * matrixColumnSize]);
        }
        printf("\n");
    }
    printf("\n");
    printf("*************\n");

    for( int i = 0 ; i < NBLOCKS/2 ; ++i )
        for( int j = 0 ; j < NBLOCKS/2 ; ++j ){
            int sliceColumnSize = sqrt(SIZE / NBLOCKS);
            get_slice( matrix, block, SIZE, SIZE / NBLOCKS ,i*(sliceColumnSize), j*(sliceColumnSize) );
            printf("part:%d\n",1+j+i*(NBLOCKS/2));
            printSlice(block,SIZE / NBLOCKS);
            printf("*************\n");
        }


    /*for( int i = 0 ; i < NBLOCKS ; ++i ) // get all blocks (invariant: NBLOCKS == 4)
        get_slice( matrix, block, SIZE / NBLOCKS ,BLKSZ*i/2, BLKSZ*i%2 ) ;*/
    return 0;
}

Output:

matrix[0][0] ->  1 matrix[0][1] ->  2 matrix[0][2] ->  3 matrix[0][3] ->  4 matrix[0][4] ->  5 matrix[0][5] ->  6 matrix[0][6] ->  7 matrix[0][7] ->  8 
matrix[1][0] ->  9 matrix[1][1] -> 10 matrix[1][2] -> 11 matrix[1][3] -> 12 matrix[1][4] -> 13 matrix[1][5] -> 14 matrix[1][6] -> 15 matrix[1][7] -> 16 
matrix[2][0] -> 17 matrix[2][1] -> 18 matrix[2][2] -> 19 matrix[2][3] -> 20 matrix[2][4] -> 21 matrix[2][5] -> 22 matrix[2][6] -> 23 matrix[2][7] -> 24 
matrix[3][0] -> 25 matrix[3][1] -> 26 matrix[3][2] -> 27 matrix[3][3] -> 28 matrix[3][4] -> 29 matrix[3][5] -> 30 matrix[3][6] -> 31 matrix[3][7] -> 32 
matrix[4][0] -> 33 matrix[4][1] -> 34 matrix[4][2] -> 35 matrix[4][3] -> 36 matrix[4][4] -> 37 matrix[4][5] -> 38 matrix[4][6] -> 39 matrix[4][7] -> 40 
matrix[5][0] -> 41 matrix[5][1] -> 42 matrix[5][2] -> 43 matrix[5][3] -> 44 matrix[5][4] -> 45 matrix[5][5] -> 46 matrix[5][6] -> 47 matrix[5][7] -> 48 
matrix[6][0] -> 49 matrix[6][1] -> 50 matrix[6][2] -> 51 matrix[6][3] -> 52 matrix[6][4] -> 53 matrix[6][5] -> 54 matrix[6][6] -> 55 matrix[6][7] -> 56 
matrix[7][0] -> 57 matrix[7][1] -> 58 matrix[7][2] -> 59 matrix[7][3] -> 60 matrix[7][4] -> 61 matrix[7][5] -> 62 matrix[7][6] -> 63 matrix[7][7] -> 64 

*************
part:1
arr[0][0]: 1, arr[0][1]: 2, arr[0][2]: 3, arr[0][3]: 4, 
arr[1][0]: 9, arr[1][1]:10, arr[1][2]:11, arr[1][3]:12, 
arr[2][0]:17, arr[2][1]:18, arr[2][2]:19, arr[2][3]:20, 
arr[3][0]:25, arr[3][1]:26, arr[3][2]:27, arr[3][3]:28, 
*************
part:2
arr[0][0]: 5, arr[0][1]: 6, arr[0][2]: 7, arr[0][3]: 8, 
arr[1][0]:13, arr[1][1]:14, arr[1][2]:15, arr[1][3]:16, 
arr[2][0]:21, arr[2][1]:22, arr[2][2]:23, arr[2][3]:24, 
arr[3][0]:29, arr[3][1]:30, arr[3][2]:31, arr[3][3]:32, 
*************
part:3
arr[0][0]:33, arr[0][1]:34, arr[0][2]:35, arr[0][3]:36, 
arr[1][0]:41, arr[1][1]:42, arr[1][2]:43, arr[1][3]:44, 
arr[2][0]:49, arr[2][1]:50, arr[2][2]:51, arr[2][3]:52, 
arr[3][0]:57, arr[3][1]:58, arr[3][2]:59, arr[3][3]:60, 
*************
part:4
arr[0][0]:37, arr[0][1]:38, arr[0][2]:39, arr[0][3]:40, 
arr[1][0]:45, arr[1][1]:46, arr[1][2]:47, arr[1][3]:48, 
arr[2][0]:53, arr[2][1]:54, arr[2][2]:55, arr[2][3]:56, 
arr[3][0]:61, arr[3][1]:62, arr[3][2]:63, arr[3][3]:64, 
*************
Halil İbrahim Oymacı
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