Add matrix formuation section

assets/img/project_matrix_dft_im.png

assets/img/project_matrix_dft_re.png

assets/img/project_matrix_polar_im.png

assets/img/project_matrix_polar_re.png

assets/img/project_matrix_sinogram.png

assets/img/project_tiny_brain.png

assets/pdf/2004_Candes_Romberg_Tao.pdf

assets/pdf/2011_Hansen_Jorgensen.pdf

project.md