export default function mul3x3(a: Float32Array, b: Float32Array, c: Float32Array): Float32Array {

    let a11 = a[0x0], a12 = a[0x3], a13 = a[0x6];
    let a21 = a[0x1], a22 = a[0x4], a23 = a[0x7];
    let a31 = a[0x2], a32 = a[0x5], a33 = a[0x8];

    let b11 = b[0x0], b12 = b[0x3], b13 = b[0x6];
    let b21 = b[0x1], b22 = b[0x4], b23 = b[0x7];
    let b31 = b[0x2], b32 = b[0x5], b33 = b[0x8];

    c[0x0] = a11 * b11 + a12 * b21 + a13 * b31;
    c[0x3] = a11 * b12 + a12 * b22 + a13 * b32;
    c[0x6] = a11 * b13 + a12 * b23 + a13 * b33;

    c[0x1] = a21 * b11 + a22 * b21 + a23 * b31;
    c[0x4] = a21 * b12 + a22 * b22 + a23 * b32;
    c[0x7] = a21 * b13 + a22 * b23 + a23 * b33;

    c[0x2] = a31 * b11 + a32 * b21 + a33 * b31;
    c[0x5] = a31 * b12 + a32 * b22 + a33 * b32;
    c[0x8] = a31 * b13 + a32 * b23 + a33 * b33;

    return c;
}