In order that *McPhase* can calculate the standard deviation between
experimental data and the results of the simulation, some experimental data
can be given in the subdirectory *./fit*. The filenames and the data-format
are the same as the output files of *McPhas*, e.g. *mcphas.fum*, *mcphas.hkl*
etc. *McPhase* looks into the directory *./fit* and if it finds any
of these files, the standard deviation is increased correspondingly.

What measurement data can be used to calculate a standard deviation ?

*mcphas.fum*- if given in column 11, 12, 13 in
*./fit/mcphas.fum*the magnetisation in the , and direction is used for calculation of the standard deviation sta. The standard deviation is calculated as . All three components of the magnetic moment have to be given and are used.

Note that the measured data has to be given in those (H-T) points which are
calculated by mcphas in order to be used by the program to increase *sta*.
It is usually most effective to fit only few data points, because a large set
of data points will not improve the quality of the fit and only require a large
amount of calculation time.

Martin Rotter 2017-01-10