(anymap-yres anymap)
The procedures bitmap-yres, greymap-yres, graymap-yres and colormap-yres are aliases being bound to this primitive procedure for compatibilty.
The Y-resolution of the anymap is returned as an inexact float (-1.0 if undefined or unknown).
> (define bitmap (bitmap-create 100 100))
bitmap
> (anymap-yres bitmap)
-1.0