Multiply the given 4x4 matrix <code>mat</code> with <code>this</code> and return the <i>w</i> component
of the resulting 4D vector.
<p>
This method assumes the <code>w</code> component of <code>this</code> to be <code>1.0</code>.
@param mat
the matrix to multiply this vector by
@return the <i>w</i> component of the resulting 4D vector after multiplication
Multiply the given 4x4 matrix <code>mat</code> with <code>this</code> and return the <i>w</i> component of the resulting 4D vector. <p> This method assumes the <code>w</code> component of <code>this</code> to be <code>1.0</code>.
@param mat the matrix to multiply this vector by @return the <i>w</i> component of the resulting 4D vector after multiplication