This dialog is opened by the Expand... and Shrink... commands from the Matrix menu. This dialog allows to change the dimensions of a matrix, the old and new dimensions being displayed at the top of the dialog.
There are three resampling modes available: Expand for every cell, Shrink into 1x1 for every and Resize freely.
The Method box allows to choose the interpolation method to be used when calculating the values of the new cells in the resampled matrix. There are two methods available: bilinear and bicubic. The implementation of the bicubic interpolation in QtiPlot uses the algorithm from the SPLINE library written by John Burkardt. Please be aware of the fact that the bicubic interpolation fails if the matrix contains empty cells.