[25600] in Athena Bugs
linux 9.2.29: matlab
daemon@ATHENA.MIT.EDU (Omri Schwarz)
Wed Apr 14 20:33:19 2004
Message-Id: <200404150027.i3F0R7Z4007743@zygorthian-space-raiders.mit.edu>
To: bugs@mit.edu
Date: Wed, 14 Apr 2004 20:27:07 -0400
From: Omri Schwarz <ocschwar@mit.edu>
Errors-To: bugs-bounces@mit.edu
System name: zygorthian-space-raiders.mit.edu
Type and version: i686 9.2.29 (with mkserv)
Display type: Matrox Graphics, Inc. MGA G400 AGP (rev 85)
Shell: /bin/athena/tcsh
Window manager: sawfish
What were you trying to do?
Do a proper three dimensional gradient
using the numerical gradient function.
What's wrong:
a = zeros([5,5,5]);
a(:,:,1)=1;
a(:,:,5)=-1;
[x,y,z]=gradient(a);
Look at x, y and z and everything is fine.
a = zeros([5,5,5]);
a(:,1,:)=1;
a(:,5,:)=-1;
[x,y,z]=gradient(a);
Look at x,y, and z and see that everything is NOT fine.
a = zeros([5,5,5]);
a(1,:,:)=1;
a(5,:,:)=-1;
[x,y,z]=gradient(a);
Look at x,y, and z and see that everything is NOT fine.
What should have happened:
It should be putting the three output elements in the right order.
Please describe any relevant documentation references:
[FX,FY,FZ] = GRADIENT(F), when F is a 3-D array, returns the
numerical gradient of F. FZ corresponds to dF/dz, the differences
in the z direction. GRADIENT(F,H), where H is a scalar,
uses H as the spacing between points in each direction.
