Matrix Times Vector
Author: Carl Lee

Use the sliders to specify the matrix.
Then move vector B to see its image (vector C)
under the action of the matrix

a = 5 (slider from -5 to 5, step 0.1)
b = 2 (slider from -5 to 5, step 0.1)
c = 3 (slider from -5 to 5, step 0.1)
d = 4 (slider from -5 to 5, step 0.1)
text1: "\left[
\begin{array}{cc}" + (LaTeX[a]) + "&" + (LaTeX[b]) + "\\" + (LaTeX[c]) + "&" + (LaTeX[d]) + "
\right]
\end{array}"
A = Intersect(xAxis, yAxis)
e = Circle(A, 1)
B = Point(e)
C: (a * x(B) + b * y(B), c * x(B) + d * y(B))
u = Vector(A, B)
v = Vector(A, C)