NAME Simulation::Sensitivity - A general-purpose sensitivity analysis tool for user-supplied calculations and parameters SYNOPSIS use Simulation::Sensitivity; $sim = Simulation::Sensitiviy->new( calculation => sub { my $p = shift; return $p->{alpha} + $p->{beta} } parameters => { alpha => 1.1, beta => 0.2 }, delta => 0.1 ); $result = $sim->run; print $sim->text_report($result); DESCRIPTION Simulation::Sensitivity is a general-purpose sensitivity analysis tool. Given a user-written calculating function, a "base-case" of parameters, and a requested input sensitivity delta, this module will carry out a sensitivity analysis, capturing the output of the calculating function while varying each parameter positively and negatively by the specified delta. The module also produces a simple text report showing the percentage impact of each parameter upon the output. The user-written calculating function must follow a standard form, but may make any type of computations so long as the form is satisfied. It must take a single argument -- a hash reference of parameters for use in the calculation. It must return a single, numerical result. CONSTRUCTORS "new" my $sim = Simulation::Sensitivity->new( calculation => sub { my $p = shift; return $p->{alpha} + $p->{beta} } parameters => { alpha => 1.1, beta => 0.2 }, delta => 0.1 ); "new" takes as its argument a hash with three required parameters. "calculation" must be a reference to a subroutine and is used for calculation. It must adhere to the usage guidelines above for such functions. "parameters" must be a reference to a hash that represents the initial starting parameters for the calculation. "delta" is a percentage that each parameter will be pertubed by during the analysis. Percentages should be expressed as a decimal (0.1 to indicate 10%). As a constructor, "new" returns a Simulation::Sensitivity object. PROPERTIES "calculation", "parameters", "delta" $sim->calculation()->({alpha=1.0, beta=1.0}); %p = %{$sim->parameters()}; $new_delta = $sim->delta(.15); The parameter values in a Simulation::Sensitivity object may be retreived or modified using get/set accessors. With no argument, the accessor returns the value of the parameter. With an argument, the accessor sets the value to the new value and returns the new value. METHODS "base" $base_case = base(); This method returns the base-case result for the parameter values provided in the constructor. "run" $results = run(); This method returns a hash reference containing the results of the sensitivity analysis. The keys of the hash are the same as the keys of the parameters array. The values of the hash are themselves a hash reference with each key representing a particular case in string form (e.g. "+10%" or "-10%") and the value equal to the result from the calculation. A simple example would be: { alpha => { "+25%" => 5.25, "-25%" => 4.75 }, beta => { "+25%" => 6, "-25%" => 4 } } "text_report" $report = text_report( $results ); This method generates a text string containing a simple, multi-line report. The only parameter is a hash reference containing a set of results produced with "run". BUGS Please report any bugs or feature using the CPAN Request Tracker. Bugs can be submitted by email to "bug-Simulation-Sensitivity@rt.cpan.org" or through the web interface at <http://rt.cpan.org/Public/Dist/Display.html?Name=Simulation-Sensitivity > When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature. AUTHOR David A Golden (DAGOLDEN) dagolden@cpan.org <http://dagolden.com/> COPYRIGHT Copyright (c) 2006 by David A Golden This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. 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