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NAG Toolbox

NAG Toolbox: nag_issue_warnings

Purpose

nag_issue_warnings determines how errors from NAG Toolbox functions are signalled.

Syntax

warnp = nag_issue_warnings
warnp = nag_issue_warnings(setwarn)

Description

nag_issue_warnings determines whether errors in NAG Toolbox routines are signalled by errors of the style NAG:error_sv (where s is p to indicate a positive value and n to indicate a negative value, and nis an integer) or via the return value of an error flag (ifail or info). Using NAG:error_sv is the default behaviour.
warnp = nag_issue_warnings returns the current setting (true or false).
warnp = nag_issue_warnings(setwarn) where setwarn is a logical scalar sets the current behaviour to either true or false.
Tips
Note that this allows for two styles of programming. Errors can be caught using a try/catch block while the return values of an error flag can be interogated. Note that some routines will issue warnings even if nag_issue_warnings is set to false if the return values of some of the output parameters are useful.
See also try/catch error section in Calling NAG Routines from MATLAB.

References

None.

Parameters

Input Parameter

1:     setwarn – logical scalar
If this parameter is used, then the error behaviour is set to use warnings and report errors via ifail or inform parameter (true), or set to raise MATLAB exceptions (false).

Output Parameter

1:     warnp – logical scalar
Reports the current error behaviour.

Error Indicators and Warnings

None.

Example

[result, abserr, ~, ~, ifail] = d01aj(@(x)1/x,0,1,1e-5,1e-5)
??? Error using ==> d01aj
d01aj returned an error indicator (1) 
nag_issue_warnings(true)
ans =
     1
[result, abserr, ~, ~, ifail] = d01aj(@(x)1/x,0,1,1e-5,1e-5)
Warning: d01aj returned a warning indicator (1) 
result =
  145.6489
abserr =
    9.3506
ifail =
                    1

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NAG Toolbox

© The Numerical Algorithms Group Ltd, Oxford, UK. 2009