Simple diffusion equation solver. It's easy to set boundary conditions or have coupled diffusion equations, which was very useful for the signal relay modeling project reported in,
Alex C. Szatmary, Ralph Nossal, Carole A. Parent*, Ritankar Majumdar*, Modeling neutrophil migration in dynamic chemoattractant gradients: assessing the role of exosomes during signal relay”. Molecular Biology of the Cell 28:23, 3457–3470 (2017).