INTERPOLATE-MAP

This convolves from the old cube to a new one, using a gaussian beam of the specified ``beam width'', as a convolving function in order to assign values to unmeasured points, to interpolate onto a finer grid, or to get better S/N on low spatial frequency data. Thus interpolating the map leads to a loss in apparent resolution. Interpolation may be applied at this time, in which case you will need a working set quota sufficient to contain two complete cubes, as one is interpolated onto the other, or, alternatively, interpolation can be specified as taking place ``on demand'' -- that is, interpolated spectra are produced from the uninterpolated cube as and when they are required by the plotting command. This uses less memory, but the individual plotting commands may execute more slowly due to the greater number of disk accesses. Interpolation on demand has the added advantage that the interpolation can be altered at will, without having to reopen the map and wait for the cube actually to be interpolated. In the former case (immediate interpolation) the interpolation may proceed rather slowly for a large map/cube, so the current row number is displayed as reassurance that something is happening. The choice is yours. During INTERPOLATE-MAP you also specify a (gaussian) convolving function for the velocity dimension of the cube. This convolving function is only applied if velocity is one of the map axes, and is applied only after the map has been extracted from the cube. It thus provides a method for smoothing the velocity dimension of a position-velocity diagram.

Relevant flags:

BEAM_FWHM	R4	Full width at half maximum of gaussian ``beam'' to be used in interpolating the map.
BEAM_EXTENT	R4	Maximum radius of interpolating function.
VEL_WIDTH	R4	Full width at half maximum of gaussian to be used in convolving velocity dimension.
VEL_EXTENT	R4	Maximum extent of velocity convolving function.
*CUBE_INTERPOLAT	L4	The `current cube' has been interpolated.

Examples:

    >> interpolate-map
    Beam size FWHM? (arcsecs) [ 20.0] 20
    Truncate spatial interpolating fn @ radius? (arcsecs) [ 25.0] 25
    Velocity convolving fn FWHM? [  0.0] 0
    Truncate velocity convolving fn @ radius? [  2.0] 0
    Interpolate on demand (rather than now)? (Y/N) [N] n

    Weights array:
       1.00000    0.50000    0.06250
       0.50000    0.25000    0.03125
       0.06250    0.03125    0.00391
    Getting virtual memory for new cube...
          39780 bytes required

    This may take a little while:
    Row being interpolated

        1
        :
        9
    ..

    >> interpolate-map
    Beam size FWHM? (arcsecs) [ 12.0] 15
    Truncate spatial interpolating fn @ radius? (arcsecs) [ 18.0] 20
    Velocity convolving fn FWHM? [  0.0] 0
    Truncate velocity convolving fn @ radius? [  2.0] 0
    Interpolate on demand (rather than now)? (Y/N) [N] y

    Weights array:
       1.00000    0.29163    0.00723
       0.29163    0.08505    0.00211
       0.00723    0.00211    0.00005
    ..