From: alice@ATHENA.MIT.EDU
Message-Id: <9106140414.AA17773@M48-206-2.MIT.EDU>
To: bug-at@ATHENA.MIT.EDU
Subject: some bugs and fixes for AtPlotter and AtContourPlot
Date: Fri, 14 Jun 91 00:14:27 EDT


Here are some bugs and fixes I found/applied while using these widgets
(the source can be found in /mit/10.362/src/Xg)

CHANGES:
2/18/91 
AtPlotter: 
	Check XtIsManaged before XClearArea
	 AtPlotterSetAxisBounds now checks if realized before redraw.
	layout.width and .height might just be zero by accident
	of random arithmetic  - check for that in AtPlotterLayout
AtContourPlot: 
	SetValues lines 232 & 240 - check that y/xPoints!=NULL
AtContourPlot:
	range of axes based on NumPoints rather than min/max. changed it
	so that the range of the x/y axes is based on min/max.
	lines 686 and 691 in GetValue calculate the x and y positions
	incorrectly; the index into Points is also incorrect
	changed GetValue into macros GetXValue and GetYValue
AtContourPlot:
	somethings's wrong with the x,y-coord - on a ramp l to r or b to
	t.  the lines go outside of the plot.  it may stem from changes
	I've made. has been fixed with the following.
AtContourPlot:
	Added check for x/yNumPoints equal to 0 in Initialize
	Check that contours!=0 before calc of contour interval
	contour interval should be (max-min)/(ncontours+1) instead
	of dividing only by ncontours, since the number of spaces is
	one greater than the number of contours.
	range on line 568 should be min+interval up to max-interval.
	looks like the original is a kludge to correct for the preceding
	bug.
AtContourPlot:
	Put procedure AddLine in-line to save a procedure call
	changed Triangle to check for a contour lying on p3 as well
	(p3==2.0). this fixes the bug which causes contours on grid
	lines to appear outside the plot.

AtPlot:
	any plot should assume that the memory allocated to its
	data has been freed; after copying, the original data should not
	be referenced again.  no changes actually made yet.


Tim Wall, Parsons Lab
alice@athena.mit.edu
alice@maya.mit.edu