iTextSharp.text.pdf.parser.Matrix.Multiply C# (CSharp) Method

        public Matrix Multiply(Matrix by)
        {
            Matrix rslt = new Matrix();

            float[] a = vals;
            float[] b = by.vals;
            float[] c = rslt.vals;

            c[I11] = a[I11]*b[I11] + a[I12]*b[I21] + a[I13]*b[I31];
            c[I12] = a[I11]*b[I12] + a[I12]*b[I22] + a[I13]*b[I32];
            c[I13] = a[I11]*b[I13] + a[I12]*b[I23] + a[I13]*b[I33];
            c[I21] = a[I21]*b[I11] + a[I22]*b[I21] + a[I23]*b[I31];
            c[I22] = a[I21]*b[I12] + a[I22]*b[I22] + a[I23]*b[I32];
            c[I23] = a[I21]*b[I13] + a[I22]*b[I23] + a[I23]*b[I33];
            c[I31] = a[I31]*b[I11] + a[I32]*b[I21] + a[I33]*b[I31];
            c[I32] = a[I31]*b[I12] + a[I32]*b[I22] + a[I33]*b[I32];
            c[I33] = a[I31]*b[I13] + a[I32]*b[I23] + a[I33]*b[I33];

            return rslt;
        }

        virtual public void TestMultiply()
        {
            Matrix m1 = new Matrix(2, 3, 4, 5, 6, 7);
            Matrix m2 = new Matrix(8, 9, 10, 11, 12, 13);
            Matrix shouldBe = new Matrix(46, 51, 82, 91, 130, 144);

            Matrix rslt = m1.Multiply(m2);
            Assert.AreEqual(shouldBe, rslt);
        }