QtiPlot includes quick access to the most useful functions for fitting.
This command is used to fit a curve which has a linear shape.
The results will be given in the Log panel:
This command is used to fit a polynomial function to data which has a curvilinear shape. Results are be given in the Log panel
This command is used to fit a curve which has a sigmoidal shape. The function used is:
in which A1 is the low Y limit, A2 is the high Y limit, x0 is the inflexion (half amplitude) point and dx is the width.
When the X axis is using a logarithmic scale, the Fit Boltzmann (sigmoidal) command uses the Logistical equation for fitting:
where A1 is the initial Y value, A2 is the final Y value, x0 is the inflexion point (center) and p is the power.
This command is used to fit a curve which has a bell shape. The function used is:
in which A is the height, w is the width, xc is the center and y0 is the Y-values offset.
This command is used to fit a curve which has a bell shape. The function used is:
in which A is the area, w is the width, xc is the center and y0 is the Y-values offset.