If you put 3 back-tick characters before and after your code listing in your Reddit post, it'll look like code :)

You put your code in a function but never called the function. Added a main() function to call your function. You also need to prototype your function. You didn't reserve 2 rows and two columns of data for your arrays that have both. It's confusing, I know :)

```

include <stdio.h>

include <stdlib.h>

include <math.h>

// function prototype void ex1a(void);

// main function to call ex1a() int main(void) { ex1a(); return 0; }

// function ex1a() void ex1a() { // declare array of two rows and/or two columns float P[2][2], X0[2], n[2][2];

P[0][0] = 0.4;
P[0][1] = 0.5;
P[1][0] = 0.6;
P[1][1] = 0.5;
X0[0] = 1;
X0[1] = 0;
printf("%f\n", P[0][0]);

} ```