Accuracy of the interpolation procedure in mass. Original tracks at a given mass are compared to tracks interpolated between the two basic masses encompassing the given mass. The color-coded data represents the difference of the logarithm of the radius (left panel), the logarithm of the effective temperature (middle panel), and the logarithm of the age (right panel) of equivalent models between the basic and interpolated tracks. All tracks are at Z_init = 0.014.