matrix multiplication note to self

matrix multiplication, matrix * point using mathutils:

	from mathutils import Matrix, Vector
	>>> M = Matrix([[1, 0, 0, 0],[0, 1, 0, 0],[0, 0, -1.2, -2.2],[0, 0, -1, 0]])
	>>> vec_1 = Vector((0,0,-1,1))
	>>> vec_2 = Vector((0,11,-11,1))
	>>> vec_3 = Vector((0,4,-6,1))
	>>> for vec in [vec_1, vec_2, vec_3]: M*vec
	...
	Vector((0.0, 0.0, -1.0, 1.0))
	Vector((0.0, 11.0, 11.0, 11.0))
	Vector((0.0, 4.0, 5.0, 6.0))

view raw mathutils_testing.py hosted with ❤ by GitHub

using numpy:

	import numpy as np
	mdata = "[1 0 0 0; 0 1 0 0; 0 0 -1.2 -2.2; 0 0 -1 0]"
	M = np.matrix(mdata)
	vec_1 = np.array([0,0,-1,1])
	vec_2 = np.array([0,11,-11,1])
	vec_3 = np.array([0,4,-6,1])
	for vec in [vec_1, vec_2, vec_3]:
	print(M.dot(vec))

view raw numpy_testing.py hosted with ❤ by GitHub

and three.js too

	// because 4*4 is inferred, the matrix is vectorized (flattened)
	var M = new THREE.Matrix4(1, 0, 0, 0, 0, 1, 0, 0, 0, 0, -1.2, -2.2, 0, 0, -1, 0);
	var vec_1 = new THREE.Vector4( 0, 0, -1, 1);
	var vec_2 = new THREE.Vector4( 0, 11,-11, 1);
	var vec_3 = new THREE.Vector4( 0, 4, -6, 1);
	[vec_1, vec_2, vec_3].forEach(function(vec,i){
	var vector_new = vec.applyMatrix4(M);
	console.log(vector_new)
	})

view raw matrix multiplication.js hosted with ❤ by GitHub

references

http://www.scipy.org/NumPy_for_Matlab_Users
http://docs.scipy.org/doc/numpy/reference/generated/numpy.matrix.html