jabble
Class ProblemSolver

java.lang.Object
  jabble.ProblemSolver

public class ProblemSolver
extends java.lang.Object

The master class that brings all objects together to solve a given problem.

Constructor Summary

ProblemSolver(Problem problem)
Creates a new ProblemSolver for the given Problem.

Method Summary

ProblemSolver	addIndicator(java.lang.String shorthand) Allows to create simple indicators for aggregate functions of a field.
ProblemSolver	addIndicator(java.lang.String name, Indicator indicator) Adds the given indicator so that it's value is computed and saved.
ProblemSolver	dontEvolveLastCoordinate() Tells the ProblemSolver not to evolve the last coordinate, which is typically the time coordinate and is evolved with t = previousT + dt.
long	getElapsedMillisec() Returns the time the computation took in milliseconds.
java.util.Date	getEndTime() Returns the time at which the actual computation ended.
int	getNPerformedIterations() Returns the number of iterations actually performed during the resolution.
java.util.Date	getStartTime() Returns the time at which the actual computation started.
ProblemSolver	recordError(java.lang.String filename) Changes the name of the file to which the error field output is saved.
ProblemSolver	recordEvolution(java.lang.String filename, int interval) Changes the filename for saving the output, and sets the number of iterations between two saves.
ProblemSolver	recordEvolutionInterval(int interval) Saves the output of the computation every interval number of iterations.
ProblemSolver	setConstraintEvolver(Evolver evolver, int maxIterations, java.lang.String fieldName, double truncationError) Changes the constraint evolver.
void	setDataStructuresFactory(java.lang.String dataStructuresFactory) Changes the implementation of the data structures.
void	setDebug(boolean debug) Turns debugging on and off.
ProblemSolver	setEvolver(Evolver evolver) Specifies which Evolver should be used for the evolution.
ProblemSolver	setFreeEvolution(boolean freeEvolution) Solves the problem using Free Evolution.
ProblemSolver	setNumberOfIterations(int nIterations) Specifies the number of iterations to be done to compute the solution.
ProblemSolver	setStopTrigger(Trigger stopTrigger) Sets a Trigger to stop the evolution if a condition is met (look at the stopOnXxx methods to stop on simple conditions).
void	solve() Starts the solution of the given problem with all the given options.
ProblemSolver	stopAfterTimePeriod(long millisec) Stops the evolution after a given period of time.
ProblemSolver	stopOnConvergence(java.lang.String fieldName, double truncationError) Stops the evolution when the change of value for the given field is less than the truncationError.
ProblemSolver	stopOnIndicatorOutsideRange(java.lang.String indicatorShorthand, double min, double max) Stops the evolution when the value of the indicator is outside the given range.
ProblemSolver	stopOnIndicatorOverThreshold(java.lang.String indicatorShorthand, double threshold) Stops the evolution when the value of the indicator is above the given threshold.
ProblemSolver	stopOnIndicatorUnderThreshold(java.lang.String indicatorShorthand, double threshold) Stops the evolution when the value of the indicator is below the given threshold.
ProblemSolver	stopOnNanOrInfinity() Stops the evolution if a NAN or Infinity value appears on any Field.
ProblemSolver	verifyResult(double tolerance) Compares the result of the evolution with the exact solution given in the problem.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ProblemSolver

public ProblemSolver(Problem problem)

Creates a new ProblemSolver for the given Problem.

Parameters:

problem - a Jabble Problem

Method Detail

setDebug

public void setDebug(boolean debug)

Turns debugging on and off. Has to be changed before any calculation is done. Default is on.

Parameters:

debug - new debugging setting

setDataStructuresFactory

public void setDataStructuresFactory(java.lang.String dataStructuresFactory)

Changes the implementation of the data structures.

Parameters:

dataStructuresFactory - class name that implements the DataStructuresFactory

addIndicator

public ProblemSolver addIndicator(java.lang.String name,
                                  Indicator indicator)

Adds the given indicator so that it's value is computed and saved.

Parameters:

name - the name given to distinguish the indicator

indicator - an indicator object

Returns:

this ProblemSolver

addIndicator

public ProblemSolver addIndicator(java.lang.String shorthand)

Allows to create simple indicators for aggregate functions of a field.

For example, given the field 'phi' in the equation, we can have the following:

• totalPhi - integral of the field phi
• averagePhi - average of the field phi
• minPhi - minimum value of phi
• maxPhi - maximum value of phi

Parameters:

shorthand - the name of the indicator (such as totalEnergy or averageMomentum)

Returns:

this ProblemSolver

setEvolver

public ProblemSolver setEvolver(Evolver evolver)

Specifies which Evolver should be used for the evolution. If not specified, the default will be taken from the problem (see Problem.getDefaultEvolver).

Parameters:

evolver - the evolver to be used to compute the solution

Returns:

this ProblemSolver

setConstraintEvolver

public ProblemSolver setConstraintEvolver(Evolver evolver,
                                          int maxIterations,
                                          java.lang.String fieldName,
                                          double truncationError)

Changes the constraint evolver.

Parameters:

evolver - the Evolver to use to solve the constraints

maxIterations - number of iterations for the constraints evolver

fieldName - the name of the field to check for the truncation error

truncationError - acceptable truncation error

Returns:

this ProblemSolver

setFreeEvolution

public ProblemSolver setFreeEvolution(boolean freeEvolution)

Solves the problem using Free Evolution. In free evolution, the contraints are solved only on the initial conditions.

Parameters:

freeEvolution - true to set free evolution

Returns:

this ProblemSolver

setNumberOfIterations

public ProblemSolver setNumberOfIterations(int nIterations)

Specifies the number of iterations to be done to compute the solution. If a stop condition is specified, fewer number of iterations will be computed.

Parameters:

nIterations - a positive integer

Returns:

this ProblemSolver

setStopTrigger

public ProblemSolver setStopTrigger(Trigger stopTrigger)

Sets a Trigger to stop the evolution if a condition is met (look at the stopOnXxx methods to stop on simple conditions). By default, no stop condition is set.

Parameters:

stopTrigger - a Trigger object that will stop the evolution

Returns:

this ProblemSolver

dontEvolveLastCoordinate

public ProblemSolver dontEvolveLastCoordinate()

Tells the ProblemSolver not to evolve the last coordinate, which is typically the time coordinate and is evolved with t = previousT + dt.

Returns:

this ProblemSolver

stopOnConvergence

public ProblemSolver stopOnConvergence(java.lang.String fieldName,
                                       double truncationError)

Stops the evolution when the change of value for the given field is less than the truncationError.

Parameters:

fieldName - the name of a field

truncationError - the truncation allowed

Returns:

this ProblemSolver

stopOnIndicatorOutsideRange

public ProblemSolver stopOnIndicatorOutsideRange(java.lang.String indicatorShorthand,
                                                 double min,
                                                 double max)

Stops the evolution when the value of the indicator is outside the given range. Useful to monitor quantities that the solution must conserve (i.e. totalProbability, totalEnergy, ...), and to make the evolution stop as soon as that condition is violated.

Parameters:

indicatorShorthand - an indicator (i.e. totalProbability, averagePhi, ...)

min - the minimum value the indicator can have before stopping the evolution

max - the maximum value the indicator can have before stopping the evolution

Returns:

this ProblemSolver

stopOnIndicatorOverThreshold

public ProblemSolver stopOnIndicatorOverThreshold(java.lang.String indicatorShorthand,
                                                  double threshold)

Stops the evolution when the value of the indicator is above the given threshold. Useful to monitor quantities that must be under a certain value for the solution to be valid (i.e. maxPressure, averageMomentum, ...), and to make the evolution stop as soon as that condition is violated.

Parameters:

indicatorShorthand - the name of the indicator

threshold - the maximum value the indicator can have before stopping the evolution

Returns:

this ProblemSolver

stopOnIndicatorUnderThreshold

public ProblemSolver stopOnIndicatorUnderThreshold(java.lang.String indicatorShorthand,
                                                   double threshold)

Stops the evolution when the value of the indicator is below the given threshold. Useful to monitor quantities that must be over a certain value for the solution to be valid (i.e. minDensity, averageMass, ...), and to make the evolution stop as soon as that condition is violated.

Parameters:

indicatorShorthand - the name of the indicator

threshold - the minimum value the indicator can have before stopping the evolution

Returns:

this ProblemSolver

stopAfterTimePeriod

public ProblemSolver stopAfterTimePeriod(long millisec)

Stops the evolution after a given period of time.

Parameters:

millisec - the period of time expressed in milliseconds

Returns:

this ProblemSolver

stopOnNanOrInfinity

public ProblemSolver stopOnNanOrInfinity()

Stops the evolution if a NAN or Infinity value appears on any Field. In theory, this should help halting the calculation when an instability is found. Unfortunately, diverging to the point of reaching an infinity takes some time, so one is better off using a stopOnIndicatorOutsideRange to block the evolution beforehand.

Returns:

this ProblemSolver

verifyResult

public ProblemSolver verifyResult(double tolerance)

Compares the result of the evolution with the exact solution given in the problem.

Parameters:

tolerance - the maximum difference allowed between calculated solution and exact solution

Returns:

this ProblemSolver

recordEvolution

public ProblemSolver recordEvolution(java.lang.String filename,
                                     int interval)

Changes the filename for saving the output, and sets the number of iterations between two saves.

Parameters:

filename - the name of the output file

interval - number of iterations between saves

Returns:

this ProblemSolver

recordEvolutionInterval

public ProblemSolver recordEvolutionInterval(int interval)

Saves the output of the computation every interval number of iterations.

Parameters:

interval - number of iterations between saving to the output

Returns:

this ProblemSolver

recordError

public ProblemSolver recordError(java.lang.String filename)

Changes the name of the file to which the error field output is saved.

Parameters:

filename - the name of a file

Returns:

this ProblemSolver

solve

public void solve()

Starts the solution of the given problem with all the given options.

getStartTime

public java.util.Date getStartTime()

Returns the time at which the actual computation started.

Returns:

Date when the computation started

getEndTime

public java.util.Date getEndTime()

Returns the time at which the actual computation ended.

Returns:

Date when the computation ended

getElapsedMillisec

public long getElapsedMillisec()

Returns the time the computation took in milliseconds.

Returns:

time taken by the computation

getNPerformedIterations

public int getNPerformedIterations()

Returns the number of iterations actually performed during the resolution.

Returns:

the number of iterations