function rotateY(m, angleInRadians, dst) {
    dst = dst || new MatType(16);

    var m00 = m[0 * 4 + 0];
    var m01 = m[0 * 4 + 1];
    var m02 = m[0 * 4 + 2];
    var m03 = m[0 * 4 + 3];
    var m20 = m[2 * 4 + 0];
    var m21 = m[2 * 4 + 1];
    var m22 = m[2 * 4 + 2];
    var m23 = m[2 * 4 + 3];
    var c = Math.cos(angleInRadians);
    var s = Math.sin(angleInRadians);

    dst[ 0] = c * m00 - s * m20;
    dst[ 1] = c * m01 - s * m21;
    dst[ 2] = c * m02 - s * m22;
    dst[ 3] = c * m03 - s * m23;
    dst[ 8] = c * m20 + s * m00;
    dst[ 9] = c * m21 + s * m01;
    dst[10] = c * m22 + s * m02;
    dst[11] = c * m23 + s * m03;

    if (m !== dst) {
      dst[ 4] = m[ 4];
      dst[ 5] = m[ 5];
      dst[ 6] = m[ 6];
      dst[ 7] = m[ 7];
      dst[12] = m[12];
      dst[13] = m[13];
      dst[14] = m[14];
      dst[15] = m[15];
    }

    return dst;
  }
Modifies the given 4-by-4 matrix by a rotation around the y-axis by the given
angle.
@param {module:twgl/m4.Mat4} m The matrix.
@param {number} angleInRadians The angle by which to rotate (in radians).
@param {module:twgl/m4.Mat4} [dst] matrix to hold result. If none new one is created..
@return {module:twgl/m4.Mat4} m once modified.
@memberOf module:twgl/m4