Question

Anybody good with java programming? I need help with multiplying matrices in java.

Answer 1

i can try to fix your code, im a bit rusty but ill see if the math is right

Answer 2

Ok, thank you for your willingness to help me. Here is my matrix multiplication method.

Answer 3

public class Matrix extends Object
{

// postcondition: all elements in the return value are in the range of 0...mod-1
public static int[][] mult(int[][] a, int[][] b, int mod)
{
int ra = a.length;
int ca = a[0].length;
int rb = b.length;
int cb = b[0].length;
int[][] mult = new int[ra][cb];

for (int r = 0; r < ra; r++)
{
for (int c = 0; c < cb; c++)
{
for (int i = 0; i < ca; i++)
{
mult[r][c] += a[r][i] * b[i][c];
}
}
}
return mult;
}
public static void main(String[] args)
{
int[][] a = {{2, 1, 3}, {6, 5, 9}}, b = {{4, 6, 8}, {7, 1, 3}};
System.out.println("a*b="+java.util.Arrays.deepToString(Matrix.mult(a, b, 11)));
//System.out.println("det(a)="+Matrix.det(a, 11));
}
}

Answer 4

Copy paste this code to compilejava.net

Answer 5

hi im here

Answer 6

okay so lets do this

Answer 7

I need to know why I'm getting an index out of bounds error.

Answer 8

you mixing up col and rows

Answer 9

What? How?

Answer 10

okay so A.length ==?

Answer 11

hmm it looks right

Answer 12

try changing it to ra-1 see if it fixes it

Answer 13

oh wait it say index out of range for mult

Answer 14

you can try making sure the size of mult exists already

Answer 15

define mult to be a zero matrix with col of A and rows of B

Answer 16

its rows are Col of A and its col are rows of B