function subtract$3(out, a, b) {
    out[0] = a[0] - b[0];
    out[1] = a[1] - b[1];
    out[2] = a[2] - b[2];
    out[3] = a[3] - b[3];
    out[4] = a[4] - b[4];
    out[5] = a[5] - b[5];
    out[6] = a[6] - b[6];
    out[7] = a[7] - b[7];
    out[8] = a[8] - b[8];
    out[9] = a[9] - b[9];
    out[10] = a[10] - b[10];
    out[11] = a[11] - b[11];
    out[12] = a[12] - b[12];
    out[13] = a[13] - b[13];
    out[14] = a[14] - b[14];
    out[15] = a[15] - b[15];
    return out;
  }
Subtracts matrix b from matrix a

@param {mat4} out the receiving matrix
@param {ReadonlyMat4} a the first operand
@param {ReadonlyMat4} b the second operand
@returns {mat4} out