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TMtxExpression.DefineDouble Method
TMtxExpression Class | TMtxExpression Members | MtxParseExpr Namespace | public | Example | See Also
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Defines new double variable.

Pascal
function DefineDouble(const AVarName: string): TDoubleValue;
Description

If variable with name AVarName already was definded, it will be redefined and all expressions which contain the symbol AVarName will be recompiled before the next evaluation.

See Also
Example

Use parser to evaluate the "Sqrt(X*X + Y*Y)" formula where x=3 and y=4.

uses MtxParseExpr, MtxParseClass; procedure Example(MyParser: TMtxExpression); var x,y: TDoubleValue; res: double; begin // 1. Define variables x := MyParser.DefineDouble('x'); y := MyParser.DefineDouble('y'); // 2. Set values x.DoubleValue := 3.0; y.DoubleValue := 4.0; // 3. Add formula and evaluate, MyParser.AddExpr('Sqrt(x*x+y*y)'); res := MyParser.EvaluateDouble; // res = 5.0 end;
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