Select the Spectra Interpolation tab in the Spectrum Definition dialog to interpolate spectra.
The upper part of the dialog contains a field with a co-ordinate system in which spectra selected for interpolation and the resulting spectrum are defined. To interpolate spectra, do the following.
The diagram of the interpolated spectrum will display as red in the coordinate system. The resulting spectrum will also be added to the list of spectra defined to date.
When the interpolated spectra are defined in other interval (for example, one spectrum is defined in the [0;2,5] interval, and the other in the [0;3,0] interval), then the value of the first spectrum will be extrapolated flat in the interval (2,5;3,0).