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I need a program in Delphi that get one variable equation from Edit1 such as "F(x)=4*X+2*log(x)+4*power(X,2)"
and get X value variable from Edit2 then show the result F(X) in Edit3. Please help me.

Thanks.

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5 Answers 5

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You can also check out JCL, which comes with an expression evaluator in the file JclExprEval.pas. It's free and open source.

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You probably need to have a look at this component - TbcParser.

https://www.mathparsers.com/formula-parser-for-delphi/

This component has source code included.

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Thank you, replaced it with a working link
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Have a look at

http://www.efg2.com/Lab/Library/Delphi/MathFunctions/Parsers.htm

Also, if you have JEDI and/or FastReport libraries installed you can use their parsers. We use TParser10 from http://cc.embarcadero.com/item/15974 which is one of the fastest available if not the fastest. It is freeware and work flawlessly up to D2007. I heard that it works also in D2009. Not tested yet though.

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I'm the author of one of the packages on that list, Symbolic. Note that the URL there goes to the original (FPC) package. The Delphi package is at stack.nl/~marcov/symbolicdelphi.zip
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If you want to write an own implementation and not use a ready to use library this will take you some time to do. Just search for "formula parser". I would start with a tokenizer and then build a parse tree from the tokens.

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It STRONGLY depdends on your decimal separator. Use StrToFloat or in newewr versions of Delphi - TryStrToFloat.

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