This is a flat-sky CMB lensing demo for teaching.
created by Bin HU and Zhengyi Wang @ BNU
run lens_img2.py, which produces an unlensed primary CMB map according to the input spectrum.
run lens_template.py, which produces a inverse square(or cubic) lensing potential map.
run dif_matrix.py , which produce a matrix of computing 2d gradient.
run mixing.py, which produces the lensed CMB map.