CENTR

This operation takes a complex number from the top of the stack and interprets that complex number as X and Y coordinates. It then adjusts the plot minimum (see PMIN) and the plot maximum (see PMAX) so that the point specified is at the center of the plot. The current width and height of the plot given the current PPAR values is preserved but the actual plot minimum and maximum is changed.

If PPAR exists, its values are read, the new plot minimum and maximum is calculated and then PPAR is stored, overwriting its old values. If PPAR does not exist, then default values are used, the plot view repositioned with the new center point and then PPAR is stored.