subroutine xyopen(tno,dataname,status,naxis,nsize) subroutine xyclose(tno) subroutine xyread(tno,index,array) subroutine xywrite(tno,index,array) subroutine xysetpl(tno,naxis,nsize)Here xyopen opens the image data set, and readies it for reading or writing. Dataname is the name of the data set, status is either `old' or `new', depending on whether an old data set is being opened to be read, or a new data set is being created. Naxis gives the dimension of the nsize array. Naxis is always an input parameter. Nsize gives the size, along each axis of the image. When opening an old data set, nsize is filled in by xyopen, and passed back to the caller. For a new data set, nsize must be set to the size of the desired image before the open routine is called. The argument tno is the handle passed back by the open routine, and is used in all subsequent calls to identify the data set.
Xyclose closes the data set.
Xyread and xywrite read or write a single row of the image. The row number is given by index, and the pixel data is stored in array (a real array). By default, xyread and xywrite access a row in the first image of a multi-image data set. The routine xysetpl is used to change this default to another image. In this naxis gives the dimension of the nsize array, and nsize is an integer array giving the indices along the third, fourth, etc, dimension of access. For example, to access the n'th image in a cube, use: