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POMath Parser in Delphi
 

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  1. POMath Parser in Delphi
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    <p>So here is what I am trying to do:</p> <p>I would like a parser that would evaluate equations and allow me to use custom functions. So, for example, an equation could be: </p> <pre><code>cos(5) * Patient:['lat1'] </code></pre> <p>and it would let me have a function that does something if it finds Patient: in the expression. </p> <p>The program I'm working on used a parser called MathParser (http://www.myart.bz/mathparser/), which worked fine in Delphi 2007, but has problems in Delphi XE (because of unicode). The MathParser site has a new version for XE, which I installed, but some functions have been changed around and I'm trying to get it to work right.</p> <p>So, the problem seems to be with the custom function part, since everything else works fine.</p> <p>The way I'm adding the functions is:</p> <pre><code>MathParser.AddFunction('Patient:', FPatFunction, fkMethod, FunctionMethod(PatFunction, 1), False, False, vtDouble); MathParser.AddFunction('Organ:', FOrgFunction, fkMethod, FunctionMethod(OrganFunction, 1), False, False, vtDouble); </code></pre> <p>And then the functions themselves are</p> <pre><code>// patient function function CEquatCalc.PatFunction(const AFunction: PFunction; const AType: PType; const ParameterArray: TParameterArray): TValue; begin if Assigned(FPatient) and Assigned(FOrgan) then AssignDouble(Result, (FPatient as CPatientItem).GetScoreVal((Trim(ParameterArray[0].Text)), (FOrgan as COrganItem))) else if Assigned(FPatient) then AssignDouble(Result,(FPatient as CPatientItem).GetScoreVal((Trim(ParameterArray[0].Text)), NIL)); </code></pre> <p>end;</p> <pre><code>// organ function function CEquatCalc.OrganFunction(const AFunction: PFunction; const AType: PType; const ParameterArray: TParameterArray): TValue; begin AssignDouble(Result, (FOrgan as COrganItem).GetScoreVal((Trim(ParameterArray[0].Text)))); end; </code></pre> <p>The error that pops up says something like "Unknown element: lat1". Unfortunately since the component didn't come with Parser.pas (just the dcu file), I can't debug where it's happening.</p> <p>Hopefully someone knows what the problem is, and if not, could you recommend another parser that would do what I want? (and is preferably free)</p>
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    1. COSounds like a bug or a parser change in the component itself: without source, your best option would be to [contact the developer](http://www.myart.bz/mathparser/index.php?option=com_content&view=article&id=11&Itemid=13) and give them a small demo program that shows the problem (with a mockup of your math expression and the functions you need to call.)
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      1. USDavid M
 

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