##TFunctionParser
Author: Carlos García Trujillo
May 25 1999
Xalapa, Veracruz; Mexico.
Description:
This is a non visual component that can evaluate mathematical functions defined by the user on runtime.
It has as characteristic that can evaluate mathematical expressions as a common calculator, and also supports user's variables, so you can define functions of more than one variable without bigger problem.
The operators supported by this component are:
+: Addition
-: Subtraction
*: Multiplication
/: Division
^: Exponential (just supports positive numbers for the base)
(: Parenthesis that opens up.
): Parenthesis that closes.
MOD: Operator MOD. Alone for whole (If it is used with floating
the value is rounded)
ABS (Range: -1e4932 ..1e4932)
ATAN (Range: -1e4932 ..1e4932)
COS (Range: -1e18 ..1e18)
EXP (Range: -11356 ..11356)
LN (Range: 0 ..1e4932)
ROUND (Range: -1e9 ..1e9)
SIN (Range: -1e18 ..1e18)
SQRT (Range: 0 ..1e4932)
SQR (Range: -1e2446 ..1e2446)
TRUNC (Range: -1e9 ..1e9)
##Use:
Firstly, in the property Funcion, the string that it contains the function or expression to evaluate should be assigned, later calls himself to the method "Parse", if no error happens in the process of Parser, the value of the evaluated function will be returned in the ParseValor property, and if an error happens, the property "ParseError" returns a "True", and the event "OnParserError" is fired, where one of those specific parameters shows the error type that happened in the process of Parser...
To be able to respond to definitions of Variables inside the Expression or function to evaluate, you can use the event "OnPideVariable" which is an event that it is fired when the parser finds a variable and requests a numeric value to substitute it, the opposing variable spends as the oneVariable parameter, and the Value with which the variable should be substituted it is returned in the Par�metro value, another parameter is also included for to determine that it is not a permissible variable, returning in the parameter "Found" a "False". The way that you define the code for this event will determine if the parser will be CaseSensitive or CaseInsensitive.
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The demo included is a clear example of the use of this component, evaluating and plotting functions of 2 variables, and dislpaying a 3D graph.
This component works for all the versions of Delphi, please communicate if you have problems proving this component with some of these versions.
To install it follow these steps:
-
- in Delphi you go to the menu: "Component / Install Component" (this is in Delphi 2 +, since the way of installing components is different in Delphi 1: OPTIONS / INSTALL COMPONENTS") and then select the file "FuncionParser.pas"
2.- if you can't install the component individually, then you can install the package "CGTPkg.dpk" opening the package and choosing "Install"
3.- the component will settle in the Tab of "CGT" like "FuncionParser ".
This component is Freeware, and you are free of to redistribute it and to use it in your applications, alone please mentions my name in the documentation of your program, (if it is not a lot of nuisance), or send me a postcard of gratefulness.
(Iknow i shouldn't put an exe on the repo, but it's for the purpouse that you can test it without having to install Delphi and GLScene 😉)
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