#include <stdio.h>
#include <malloc.h>

float pearson(int size, float *z1, float *z2);
void die(char *message);
void *cmalloc(int size);

int main(int argc, char *argv[]) {
    int rows = atoi(argv[1]);
    int cols = atoi(argv[2]);
    int i, j;
    int count = 0;
    int total = rows * rows / 2 - (rows / 2);
    
    fprintf(stderr, "allocating %d by %d array\n", rows, cols);
    float **data = (float **)cmalloc(rows * sizeof(float *));
    for(i = 0; i < rows; i++)
        data[i] = (float *)cmalloc(cols * sizeof(float));
    

    fprintf(stderr, "reading stdin\n");
    for(i = 0; i < rows; i++)
        if (fread(data[i], sizeof(float), cols, stdin) != cols)
              die("Error reading data from file.");

    fprintf(stderr, "computing correlations\n");
    for (i = 0; i < rows; i++) {
        for(j = i + 1; j < rows; j++) {
            pearson(cols, data[i], data[j]);
            if(count % 500000 == 0)
                fprintf(stderr, "\r%d / %d", count, total);
            count++;
        }
    }
    fprintf(stderr, "\n");
}

// ---------------------------------------------------------

float pearson(int size, float *z1, float *z2){
    int i;
    double sum = 0;
    for(i = 0; i < size; i++)
        sum += z1[i] * z2[i];
    return sum / size;
}

void die(char *message) {
    fprintf(stderr, "oopsies: %s\n", message);
    exit(1);
}

void *cmalloc(int size) {
    void *ptr = malloc(size);
    if (ptr == NULL)
        die("malloc failed");
    return ptr;
}
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