This is documentation for Mathematica 8, which was
based on an earlier version of the Wolfram Language.

# TimeConstraint

 TimeConstraintis an option for various algorithmic functions which specifies how long to spend trying a particular transformation or part of an algorithm.
• TimeConstraint->t specifies that a maximum of t seconds of CPU time should be spent trying a particular transformation or part of an algorithm.
• In functions such as Simplify and FullSimplify, settings for TimeConstraint give only the maximum time to be spent doing a particular transformation on a particular subpart; the total time spent processing the whole expression may be considerably larger.
• Changing the setting for TimeConstraint will never affect the validity of a result obtained from functions like Simplify or FullSimplify, but smaller settings may prevent the simplest possible form from being found.
• Since different computer systems run at different speeds, the same setting for TimeConstraint can lead to different results on different systems.
This takes a long time, due to trigonometric expansion, but does not yield a simplification:
TimeConstraint limits the time spent on any single transformation:
A similar example, where the transformation yields a simplification:
In this case setting TimeConstraint prevents some simplification:
This takes a long time, due to trigonometric expansion, but does not yield a simplification:
 Out[1]=
TimeConstraint limits the time spent on any single transformation:
 Out[2]=

A similar example, where the transformation yields a simplification:
 Out[1]=
In this case setting TimeConstraint prevents some simplification:
 Out[2]=
 Scope   (1)
Checking whether a condition follows from assumptions may take a long time:
If a condition does not follow from assumptions, checking this may still take a long time:
The time spent on a single condition check is restricted by the value of TimeConstraint:
With a time constraint of one second Refine cannot prove that :
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