DifCal

Calculate diffraction angles for a particular crystal with a defined orientation matrix.  New crystals can be added to the database.  Energy/wavelength can be changed. Currently knows about 4-circle, Z-Axis and Theta-Theta diffractometers as well as 2-circle, powder and amorphous diffraction modes.  Current crystals include silicon, diamond, GaAs, Muscovite (mica), graphite, many 3-5 and 2-6 crystals.  There are separate screens for setting the crystal (or creating a new one), defining the orientation matrix, defining the diffractometer mode, and calculating either angles, given h,k,l, or hkl given a set of angles.  With the larger screen of the iPad all the controls are visible on a single page.