This is a handy companion for people engaged in x-ray or neutron diffraction. It provides an easy way to calculate the diffraction angles or d-spacings for a crystal structure. When two of the parameters of Bragg's Law, λ = 2d sin(θ), are provided, the third is calculated. For example if you know energy and d-spacing then the angle θ is calculated. Also for the loaded crystal structure, it provides atomic positions, calculated values for the Kinematic and Dynamical Integrated Intensities, absorption factor, structure factor, and can further provide plots of the rocking curve, mirror reflectivity, F(000), µ, powder pattern, stereographic projection, Laue pattern, multiple reflections, and 3D model of the unit cell and 1st Brillouin zone. Atomic structure factors for X-rays and Neutrons are included. There is the same functionality on both iPhone and iPad.