RuntimeOptions

is an option for Compile that specifies runtime settings for the compiled function it creates.

Details

RuntimeOptions applies to the execution of the compiled function.
RuntimeOptions can take the following overall settings:
"Quality" optimize for quality of final results

"Speed" optimize for speed of getting results
RuntimeOptions can also take the following nested settings:

"CatchMachineOverflow"	False	whether real overflow should be caught as it happens
"CatchMachineIntegerOverflow"	True	whether integer overflow should be caught
"CompareWithTolerance"	True	whether comparisons should work similarly to SameQ
"EvaluateSymbolically"	True	whether to evaluate with symbolic arguments
"RuntimeErrorHandler"	Evaluate	a function to apply if there is a fatal runtime error executing the function
"WarningMessages"	True	whether warning messages should be emitted

	"CatchMachineOverflow"	False
	"CatchMachineIntegerOverflow"	False
	"CompareWithTolerance"	False
	"EvaluateSymbolically"	True
	"RuntimeErrorHandler"	Evaluate
	"WarningMessages"	True

	"CatchMachineOverflow"	True
	"CatchMachineIntegerOverflow"	True
	"CompareWithTolerance"	True
	"EvaluateSymbolically"	True
	"RuntimeErrorHandler"	Evaluate
	"WarningMessages"	True

open allclose all

Typically, integer arithmetic overflow is caught and the computation switches to use bignums:

Turning off runtime checks leads to maximum speed but the result can be incorrect if the numbers overflow:

Typically, machine integer overflow is caught and generates a runtime error:

Turning off machine integer overflow checking leads to faster results, which may be incorrect in some cases:

The "RuntimeErrorHandler" setting is used when there is a runtime error:

With no error, the compiled function works as normal:

If there is a runtime error, the function behaves differently:

The default is to evaluate the function symbolically with symbolic arguments:

With "EvaluateSymbolically"->False, the function returns unevaluated:

This evaluates if the symbolic argument is replaced with a number:

Sometimes symbolic evaluation does not give what you intend:

Preventing symbolic evaluation keeps the original intent:

Symbolic evaluation may be slow for expressions that expand out:

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