<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <!--Converted with LaTeX2HTML 98.1p1 release (March 2nd, 1998) originally by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds * revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan * with significant contributions from: Jens Lippmann, Marek Rouchal, Martin Wilck and others --> <HTML> <HEAD> <TITLE>Backgrounds</TITLE> <META NAME="description" CONTENT="Backgrounds"> <META NAME="keywords" CONTENT="vol2"> <META NAME="resource-type" CONTENT="document"> <META NAME="distribution" CONTENT="global"> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> <LINK REL="STYLESHEET" HREF="vol2.css"> <LINK REL="previous" HREF="node204.html"> <LINK REL="up" HREF="node203.html"> <LINK REL="next" HREF="node206.html"> </HEAD> <BODY > <!--Navigation Panel--> <A NAME="tex2html3967" HREF="node206.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="icons.gif/next_motif.gif"></A> <A NAME="tex2html3964" HREF="node203.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="icons.gif/up_motif.gif"></A> <A NAME="tex2html3960" HREF="node204.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="icons.gif/previous_motif.gif"></A> <A NAME="tex2html3966" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="icons.gif/contents_motif.gif"></A> <BR> <B> Next:</B> <A NAME="tex2html3968" HREF="node206.html">1-Dimensional Images (``Spectra'')</A> <B> Up:</B> <A NAME="tex2html3965" HREF="node203.html">2-Dimensional Images</A> <B> Previous:</B> <A NAME="tex2html3961" HREF="node204.html">Patterns</A> <BR> <BR> <!--End of Navigation Panel--> <H2><A NAME="SECTION001422000000000000000"> Backgrounds</A> </H2> The following commands may be executed within the GEOTEST context (activated with the <TT>SET/CONTEXT GEOTEST</TT> command). <P> <DL> <DT><STRONG>CREATE/RAMP</STRONG> <DD>produces square two-dimensional images of user-specified dimensions, with mean flux per pixel of 100 units, of user-specified slope of the plane, and with the plane itself sloping at a position angle. The latter can vary between 0 and 90 degrees. <P> For large slopes, the flux assigned to some pixels will be negative (-- this being dependent on the position angle). <P> <DT><STRONG>CREATE/WAVE</STRONG> <DD>produces an image with sinusoidal modulations along the horizontal axis. Again, the image is two-dimensional, of user-specified dimensions, and with user-specified amplitude and period. The <I>sin</I> function is always evaluated at the center of the pixel. The mean flux per period is 0 units. <P> </DL> <P> <BR><HR> <ADDRESS> <I>Petra Nass</I> <BR><I>1999-06-15</I> </ADDRESS> </BODY> </HTML>
