difficulty with pgband syntax

Hallo!

I've been mashing my head against the wall for a couple of hours trying to get pgband to pass me a user-defined axis coordinate. I've constructed an image (a random magnification pattern) that i want to horizontally sample a few times. I want a human being (me) to review the pattern, then use cpgband to graphically select a y-coordinate (all that is really required is this one value) where interesting features (light ray caustics... tres cool) crop up.


The following code throws an error:


char ch[1];

float slice_x,slice_y;

slice_x = 1.;

slice_y = 1.;

cpgband(5,0,0,0,slice_x, slice_y, ch);


The error is:
GML_eleven.c:620: error: incompatible type for argument 5 of 'cpgband'
GML_eleven.c:620: error: incompatible type for argument 6 of 'cpgband'


I cannot see why this is the case... I though cpgband wanted floats at argument 5 and 6?

Does anyone have any pointers on the correct implementation of cpgband? Tad lost here.

Thanks!

Aha!! pass cpgband one dimensional float arrays at argument 5 and 6 and it behaves itself very nicely. Just in case anyone was wondering.