The thermal expansion of a material is a key feature in lots of physical applications. A useful tool to quantify this property in a crystalline structure is the deformation tensor, which depends on the temperature. Using Matlab we provided a program that, given diffraction data from a material at different temperatures, infers its deformation tensor at desired temperatures and uses it to plot its 3D deformation at a given temperature through the deformation ellipsoid of the tensor. 2019/2020