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| − | An equation reader for your dictionary files.<BR>
| + | This project has migrated over to '''github'''. |
| − | {{VersionInfo}}{{Version1.5}}{{Version1.6}}
| + | |
| − | == What is it? ==
| + | |
| − | '''equationReader''' is an extension to [[OpenFOAM]] that allows you to read equations from a dictionary file, and have them evaluated at every timestep. It works for <tt>scalars</tt> and <tt>dimensionedScalars</tt>. For example: | + | |
| | | | |
| − | nu nu [0 2 -1 0 0 0 0] "1.2 + 3 * alpha^sin(pi_/6)";
| + | '''''[http://github.com/Marupio/equationReader/wiki Click here for the new website.]''''' |
| − | aScalar "nu / max(5, alpha)";
| + | |
| − | alpha 1.3;
| + | |
| | | | |
| − | == Features ==
| + | http://github.com/Marupio/equationReader/wiki |
| − | * '''Order of operations''' - it is fully compliant with the conventional order of operations to an arbitrary parenthesis depth;
| + | |
| − | * '''Flexible data sources''' - equations can use data from any <tt>dictionary</tt>, <tt>scalar</tt>, or <tt>dimensionedScalar</tt>;
| + | |
| − | * '''Equation dependency tracking''' - equations can depend on one another to an arbitrary hierarchy depth;
| + | |
| − | * '''Circular-reference detection''' - it will halt computations when a circular reference is detected;
| + | |
| − | * '''On-the-fly equation mapping''' - it will automatically perform substitution on other equations when they are needed, even if they aren't specifically called for in the solver;
| + | |
| − | * '''Dimension-checking''' - fully utilizes [[OpenFOAM]]'s built-in dimension-checking, or you can force the outcome to a specific dimension-set to quickly disable it (if you are lazy);
| + | |
| − | * '''Three modes of operation''' - you can choose from three different modes of operation to suit your needs:
| + | |
| − | :# '''stand-alone''' - this one works "out of the box" with all OpenFOAM applications. You can only use literal constants in your equations;
| + | |
| − | :# '''passive mode''' - if you create an <tt>equationReader</tt> object, you can give it data sources. This allows you to use variables, and equation substitution; and
| + | |
| − | :# '''active mode''' - if you also give <tt>equationReader</tt> pointers to your output variables, it can automatically update the values at every timestep.
| + | |
| − | | + | |
| − | == How do you use it? ==
| + | |
| − | | + | |
| − | === Syntax ===
| + | |
| − | The general syntax is:
| + | |
| − | | + | |
| − | ==== <tt>scalar</tt> or regular equation ====
| + | |
| − | An equation using this format has dimension-checking enabled (unless you turn off set dimensionSet::debug).
| + | |
| − | keyword "''equation''";
| + | |
| − | e.g.:
| + | |
| − | endTime "2*pi_/360*60";
| + | |
| − | | + | |
| − | ==== <tt>dimensionedScalar</tt> or dimensioned equation ====
| + | |
| − | If you specify dimensions, it will disable the dimension-checking and force the outcome to the given dimensionSet.
| + | |
| − | keyword name [''dimensionSet''] "''equation''";
| + | |
| − | e.g.:
| + | |
| − | nu nu [0 2 -1 0 0 0 0] "1 / (1e-5 + 2.3/4000 + SMALL_)";
| + | |
| − | '''NOTE:''' A dimensioned equation will ignore the 'name' field;
| + | |
| − | ==== Abbreviated dimensioned equation ====
| + | |
| − | Since a dimensioned equation does not need the <tt>name</tt> field, an abbreviated format is acceptable:
| + | |
| − | keyword [''dimensionSet''] "''equation''";
| + | |
| − | e.g.:
| + | |
| − | nu [0 2 -1 0 0 0 0] "1 / (1e-5 + 2.3/4000 + SMALL_)";
| + | |
| − | This format will not work in '''stand-alone''' mode.
| + | |
| − | | + | |
| − | ==== Equation syntax ====
| + | |
| − | '''equationReader''' uses the conventional order of operations '''BEDMAS''', then left to right:
| + | |
| − | | + | |
| − | * '''B'''rackets (and functions);
| + | |
| − | * '''E'''xponents;
| + | |
| − | * '''DM''' - division and multiplication; and
| + | |
| − | * '''AS''' - addition and subtraction.
| + | |
| − | | + | |
| − | Basically, if you can enter equations into Excel<ref>Excel is copyright Microsoft</ref>, you already know how to do this.
| + | |
| − | | + | |
| − | * you can use any amount of whitespace you want;
| + | |
| − | * exponents are <tt>^</tt>, for example <tt>2^3</tt> is <tt>8</tt>;
| + | |
| − | * multiplication is <tt>*</tt>, for example <tt>2*3</tt> is <tt>6</tt>;
| + | |
| − | * there is no implied multiplication - you must explicitly use <tt>*</tt>. For example:
| + | |
| − | ::<tt>2 sin(theta)</tt> <span style="color:#ff0000">'''INCORRECT'''</span>
| + | |
| − | ::<tt>2 * sin(theta)</tt> '''CORRECT'''
| + | |
| − | :and
| + | |
| − | ::<tt>2(3 + 4)</tt> <span style="color:#ff0000">'''INCORRECT'''</span>
| + | |
| − | ::<tt>2 * (3 + 4)</tt> '''CORRECT'''
| + | |
| − | | + | |
| − | '''NOTE: You cannot have numbers in your variable names.'''
| + | |
| − | | + | |
| − | ==== Mathematical constants ====
| + | |
| − | '''equationReader''' recognizes all the mathematical constants I could find in the [[OpenFOAM]] library. To specify a mathematical constant, append the regular [[OpenFOAM]] format with an underscore '_'. The available constants are:
| + | |
| − | | + | |
| − | * <tt>e_</tt> (Euler's number);
| + | |
| − | * <tt>pi_</tt>;
| + | |
| − | * <tt>twoPi_</tt>;
| + | |
| − | * <tt>piByTwo_</tt>;
| + | |
| − | * <tt>GREAT_</tt>;
| + | |
| − | * <tt>VGREAT_</tt>;
| + | |
| − | * <tt>ROOTVGREAT_</tt>;
| + | |
| − | * <tt>SMALL_</tt>;
| + | |
| − | * <tt>VSMALL_</tt>; and
| + | |
| − | * <tt>ROOTSMALL_</tt>.
| + | |
| − | | + | |
| − | ==== Functions ====
| + | |
| − | [[Contrib_equationReader/functions|Click here for a complete list of functions.]]
| + | |
| − | | + | |
| − | All the <tt>scalar</tt> and <tt>dimensionedScalar</tt> functions I could find in the [[OpenFOAM]] library have been implemented.
| + | |
| − | | + | |
| − | === Stand-alone mode ===
| + | |
| − | '''equationReader''' changes [[OpenFOAM]]'s <tt>readScalar</tt> function, and therefore all existing applications can use equation input for <tt>scalar</tt>s and <tt>dimensionedScalar</tt>s read from dictionary. Using '''stand-alone mode:'''
| + | |
| − | | + | |
| − | * you do not have to recompile the solver or application;
| + | |
| − | * you can use <tt>[[#scalar or regular equation|scalar]]</tt> and <tt>[[#dimensionedScalar or dimensioned equation|dimensionedScalar]]</tt> formats (above);
| + | |
| − | * you can use [[#Mathematical constants|mathematical constants]]; and
| + | |
| − | * you can use [[TestMarupio/functions|functions]]; but
| + | |
| − | * '''you cannot use any variables.'''
| + | |
| − | | + | |
| − | Since you cannot use variables, there is no equation substitution available in '''stand-alone mode'''.
| + | |
| − | | + | |
| − | === Passive and active mode ===
| + | |
| − | To use '''passive mode''' and '''active mode''' your solver or application has to be specifically written to use '''equationReader'''. See [[#Programming with equationReader|Programming with equationReader]].
| + | |
| − | | + | |
| − | === Debugging your equations ===
| + | |
| − | If you enter an incorrect equation '''equationReader''' should throw an error that explains exactly what is wrong with it. If you encounter a floating point exception, try using a debug flag. Add <tt>equationReader</tt> to the debug flag list in <tt>[OpenFOAM root folder]/etc/controlDict</tt>. There are two debug levels:
| + | |
| − | # Show when equations are read, parsed, and evaluated; and
| + | |
| − | # Show every operation as it is calculated.
| + | |
| − | | + | |
| − | == Programming with '''equationReader''' ==
| + | |
| − | Have a look at the demo application that '''equationReader''' comes with.
| + | |
| − | | + | |
| − | To enable the use of variables, you have to create an <tt>equationReader</tt> object, and tell it where to find its data.
| + | |
| − | <cpp>#include "equationReader.H"
| + | |
| − | // ...
| + | |
| − | equationReader eqns;
| + | |
| − | </cpp>
| + | |
| − | | + | |
| − | To give it data, use the <tt>addDataSource</tt> functions. There are three data sources '''equationReader''' will accept:
| + | |
| − | * <tt>scalars</tt>;
| + | |
| − | * <tt>dimensionedScalars</tt>; and
| + | |
| − | * <tt>dictionaries</tt>.
| + | |
| − | | + | |
| − | '''NOTE:''' I've provided access methods directly to the data storage members, so if you know what you are doing, you can direclty modify everything this way.
| + | |
| − | | + | |
| − | === Data source and output warnings ===
| + | |
| − | '''WARNING - KEEP YOUR DATA SOURCES AND OUTPUTS ON THE FREESTORE'''<br>
| + | |
| − | You will notice the <tt>addDataSource</tt> methods '''only''' accept '''pointers'''. This is deliberate because the data sources '''must be on the freestore'''. I've had a heck of a time with the debugging [http://www.cfd-online.com/Forums/openfoam-programming-development/78359-list-cannot-trusted.html|as you can see], and this is necessary for stability<ref>Stability - I've tested '''equationReader''' with 200 data sources, embedded parenthesis depth and equation substitution depth both up to 100, using <tt>icoFoam</tt>'s cavity tutorial as a back bone. I hope it works for you!</ref>.
| + | |
| − | | + | |
| − | '''WARNING - DATA SOURCES AND OUTPUTS MUST NOT GO OUT-OF-SCOPE'''<br>
| + | |
| − | Ensure that anytime '''equationReader''' is in use, all of its data is available to it. There is no way of telling when the object at the end of a pointer has been deleted. However, it ''is'' safe to let the '''equationReader''' go out-of-scope without impacting the data.
| + | |
| − | | + | |
| − | === Reading equations ===
| + | |
| − | One you've defined the data sources, you can use the <tt>readEquation</tt> method to read and parse the equations in the dictionary. This does not immediately evaluate them... use the <tt>evaluate</tt> or <tt>update</tt> methods for that.
| + | |
| − | | + | |
| − | ==== On-the-fly equation reading ====
| + | |
| − | If you have a <tt>dictionary</tt> source, '''equationReader''' will search the dictionary recursively for any unknown variables. If the variable happens to be an equation, '''equationReader''' will automatically read this equation as well. This can continue to an indefinite equation substitution depth.
| + | |
| − | | + | |
| − | === Passive mode ===
| + | |
| − | To use an equation in '''passive mode''', when you read the equation with <tt>readEquation</tt>, you do not have to specify an output variable. To get output from and equation in this manner, use <tt>evaluate</tt>. This returns a <tt>dimensionedScalar</tt> that you can assign to whatever variable you want.
| + | |
| − | | + | |
| − | Passive mode requires an <tt>evaluate</tt> command for each equation you're using.
| + | |
| − | | + | |
| − | === Active mode ===
| + | |
| − | To use an equation in '''active mode''', when you read the equation with <tt>readEquation</tt>, you must specify an output variable. Again, '''use the freestore''', and give a pointer. When you you <tt>update</tt>, '''equationReader''' will cycle through all your equations, and evaluate those with output pointers, changing the output variables in the process. If you only want to <tt>update</tt> one equation, that is also available.
| + | |
| − | | + | |
| − | '''NOTE:''' You can still use this equation passively with <tt>evaluate</tt>.
| + | |
| − | | + | |
| − | == Installation ==
| + | |
| − | To install '''equationReader''':
| + | |
| − | | + | |
| − | 0. If you are running precompiled binaries, first ensure that you can compile your copy of OpenFOAM.
| + | |
| − | | + | |
| − | 1. Download the code from [http://openfoam-extend.svn.sourceforge.net/viewvc/openfoam-extend/trunk/Breeder_1.5/libraries/equationReaderExtension/?view=tar|here].
| + | |
| − | | + | |
| − | http://openfoam-extend.svn.sourceforge.net/viewvc/openfoam-extend/trunk/Breeder_1.5/libraries/equationReaderExtension/?view=tar
| + | |
| − | | + | |
| − | 2. Edit the <tt>src/OpenFOAM/Make/files</tt> file.
| + | |
| − | | + | |
| − | 3. Around line 123 you will find <tt>"$(entry)/entryIO.C"</tt>. Add this after it:
| + | |
| − | | + | |
| − | equation = $(dictionary)/equation
| + | |
| − | $(equation)/equationReader/equationReader.C
| + | |
| − | $(equation)/equation/equation.C
| + | |
| − | $(equation)/equationOperation/equationOperation.C
| + | |
| − | | + | |
| − | 4. Save and close the file.
| + | |
| − | | + | |
| − | 5. Open a terminal window, and browse to the directory with your download.
| + | |
| − | | + | |
| − | 6. Execute:
| + | |
| − | | + | |
| − | $ tar --transform='s,equationReaderExtension,'$WM_PROJECT_DIR',' -x -v -z -f openfoam-extend-equationReaderExtension.tar.gz
| + | |
| − | $ cd $WM_PROJECT_NAME
| + | |
| − | $ wmake libso
| + | |
| − | $ cd $FOAM_APP/test/equationReaderDemo
| + | |
| − | $ wmake
| + | |
| − | $ cd $FOAM_APP/test/equationReaderTester
| + | |
| − | $ wmake
| + | |
| − | | + | |
| − | Equation reader will now be installed.
| + | |
| − | | + | |
| − | === Testing the installation ===
| + | |
| − | The code comes with two applications: a simple demo, and a more complex test program. Once '''equationReader''' is installed, there should be a new folder: <tt>$WM_PROJECT_DIR/tutorials/equationReader</tt>. Copy this into your <tt>run</tt> directory:
| + | |
| − | | + | |
| − | $ cp -rf $WM_PROJECT_DIR/tutorials/equationReader $FOAM_RUN/tutorials
| + | |
| − | | + | |
| − | '''To run the demo:'''
| + | |
| − | | + | |
| − | $ cd $FOAM_RUN/tutorials/equationReader/equationReaderDemo
| + | |
| − | $ equationReaderDemo
| + | |
| − | | + | |
| − | You can compare the output with the <tt>expectedOutput</tt> file.
| + | |
| − | | + | |
| − | '''To run the tester:'''
| + | |
| − | | + | |
| − | $ cd $FOAM_RUN/tutorials/equationReader/equationReaderTester
| + | |
| − | $ blockMesh
| + | |
| − | $ equationReaderTester
| + | |
| − | | + | |
| − | The tester runs '''equationReader''' in an environment that might be expected in a regular simulation. It shouldn't throw any errors here, but as it is beta code, please me know: [[User:Marupio|Marupio]].
| + | |
| − | | + | |
| − | == Notes ==
| + | |
| − | '''runTime modification not supported'''
| + | |
| − | :'''equationReader''' is not a <tt>regIOobject</tt>, and therefore is not capable of runTime modification (i.e. if you edit the dictionary equation while the simulation is running, nothing will happen). However, it will keep up with the change undergone by its data sources.
| + | |
| − | | + | |
| − | '''No plans for vector or label implementation'''
| + | |
| − | :There are no plans to implement vectors, labels, or any other data type. You can get around this limitation if you must, albeit in a cumbersome manner: you can break the vectors down and reassemble them; you can cast to label, etc..
| + | |
| − | | + | |
| − | == Foot notes ==
| + | |
| − | <references/>
| + | |
