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Why does TimeUsed die?

  • To: mathgroup at
  • Subject: [mg6391] Why does TimeUsed die?
  • From: "C. Woll" <carlw at>
  • Date: Sat, 15 Mar 1997 01:21:36 -0500 (EST)
  • Sender: owner-wri-mathgroup at

Hi all,

Has anyone else experience this? I am using Mma 3.0 on a SGI, and I have a
very complicated Mma program. Since I am interested in speed, I use Timing
for major subroutines. Now, in the middle of one of my subroutines, the
Timing function dies. That is, when the subroutine finishes, Timing says
that it took Null seconds. Subsequently, when I try Timing anything else,
I always get Null seconds. Moreover, I've traced the problem to TimeUsed.
When I try TimeUsed[], Mma returns TimeUsed[], not a number. So, somehow,
the function definiton for TimeUsed is being cleared. 

To get around this problem, I've written a function which does a
TimeUsed[], the subroutine, and then another TimeUsed[] to find the time
the subroutine takes. This works better, but isn't perfect. TimeUsed[]
died on me again, and the output I got was TimeUsed[]-1650. Subsequently,
the output returned is 0, since TimeUsed[]-TimeUsed[]=0.

When I go to the operating system and check the status of my Kernel, ps
returns how long my process has been running, so the information is still
available. I suppose I could write some Mma code to interrogate the
operating system for the time used.

So, has anyone else experienced this, and does anyone know of a possible


Carl Woll
Dept of Physics
U of Washington

carlw at

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