GR4_RGIVE(NX,NY,CONV,R)
This subroutine passes a two-Dimensional array to GreG as the Regular Grid array used for mapping.
NX,NY Integers, array dimensions
CONV Real*8 array of dimension 6
It contains respectively
CONV(1) Reference pixel in X (First dimension of R)
CONV(2) X User coordinate value at CONV(1)
CONV(3) X User coordinate increment per pixel (may be negative)
CONV(4)-CONV(6) same as above for Y (Second dimension of R)
R REAL array (NX,NY) to be transferred.
If R is Real*4, the array is not physically copied but its address
is computed by GreG for later use. GreG will not modify anything in
it. If of type Real*8, virtual memory is allocated to create a
Real*4 array of same dimensions.