Help Parses a mathematical expression in the string and returns the value
Author vvvv group

Credits Project JEDI Code Library (JCL)
Warnings
Bugs

related discussions

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about Expr (Value)

Syntax

The required format of the expression is Pascal style.

List of supported operations

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List of supported functions

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Random
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exp(x)
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if(x, y, z)
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random
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randg(Mean, StdDev)
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sqr(x)
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sqrt(x)
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abs(x)
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round(x)
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trunc(x)
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ln(x)
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log10(x)
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logN(x, y)
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power(x, y)
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pow(x, y)
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intpower(x, y)
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max(x, y)
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min(x, y)
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sin(x)
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cos(x)
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tan(x)
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arcsin(x)
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arccos(x)
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arctan2(x, y)
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sinh(x)
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cosh(x)
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tanh(x)
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arcsinh(x)
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arccosh(x)
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arctanh(x)
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degtorad(x)
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radtodeg(x)
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additional operands

Implicit multiplying is not supported: e.g. (X+1)(24-3) generates a syntax error and should be written (x+1)*(24-3)

Precedence

The precedence of the operands is as follows.

You can use user-defined variables in the expressions and also assign to variables using the := operand

Optimization

The compiler removes constant expressions and replaces these with the evaluated result:

4*4*x becomes 16*x
ln(5)+3*x becomes 1.609437912+3*x
limitation
4*x+3+3+5 evaluates as 4*x+3+3+5 (due to precedence rules)
whereas
4*x+(3+3+5) becomes 4*x+11

Tip: Use brackets to be sure that constant expressions are removed by the compiler

this text is mostly lifted from the readme of the Freeware component by Egbert van Nes

FAQ

Is it possible to access specific slices in the expr node? like formula which involves another slice in the spread - e.g. for some vectorstuff without splitting the spread.

sorry this is currently not possible. you would need to decompose the formula into separate nodes. or write a little c# plugin.

External Links

• http://www.dow.wau.nl/aew/ParseExpr.html TExpressionParser - A flexible and fast expression parser object for logical and mathematical functions.

Developer: Egbert van Nes