Pre-multiply scaling to this matrix by scaling the base axes by the given xy factor.
<p>
If <code>M</code> is <code>this</code> matrix and <code>S</code> the scaling matrix,
then the new matrix will be <code>S * M</code>. So when transforming a
vector <code>v</code> with the new matrix by using <code>S * M * v</code>, the
scaling will be applied last!
@param xy
the factor of the x and y component
@return this
Pre-multiply scaling to this matrix by scaling the base axes by the given xy factor. <p> If <code>M</code> is <code>this</code> matrix and <code>S</code> the scaling matrix, then the new matrix will be <code>S * M</code>. So when transforming a vector <code>v</code> with the new matrix by using <code>S * M * v</code>, the scaling will be applied last!
@param xy the factor of the x and y component @return this