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TeeChart Pro v 7.12 drawing a function y= f(x)
Posted: Tue Nov 25, 2008 2:12 pm
by 9350489
Hi Narcis,
here is my code :
Code: Select all
PROCEDURE TForm1.TeeFunction1Calculate(Sender: TCustomTeeFunction;
CONST x: Double; VAR y: Double);
BEGIN
IF (Edit1.Text = Null) OR (Edit1.Text = '') THEN exit;
y := StrToFloat(Edit1.Text);
END;
PROCEDURE TForm1.Edit1KeyDown(Sender: TObject; VAR Key: Word;
Shift: TShiftState);
BEGIN
IF key = VK_RETURN THEN
Series1.CheckDataSource;
END;
if I put
x+2 in edit1 and hit the return key
I have
EconvertError message
Can you help me ?
Didier
Posted: Fri Nov 28, 2008 10:14 am
by 9350489
Hello Narcis...
Thank you for your HELP
Didier
Posted: Fri Nov 28, 2008 10:48 am
by narcis
Hi Didier,
Sorry for the delayed reply but I needed to do some investigation on this field.
The only solution I can think of to solve this is using a mathematical formula expression parser.
Dew Research's
MtxVec 3.5 includes TMxParser which can easily handle this. You can download a trial version here:
http://www.dewresearch.com/downloads-delphi.html
Demo, available
here, includes several parser examples, together with full TeeChart support.
Posted: Fri Nov 28, 2008 1:54 pm
by 9350489
Hi Narcis,
Sorry you have asked to quickly ..
The solution you propose (parser) is interesting but seems too heavy for the moment ..
the error message is:
The project caused a Project1.exe class EConcertError exception with the message "x+2' is not a floating point value correcte.
I am not trying to solve all sorts of falling to a function to analyze ..
I would like to write a simple processing chain that sets the sake of "x+2'
the concern seems to be: "
Thank you very much for your help
Didier
Posted: Mon Dec 01, 2008 2:30 pm
by narcis
Hi Didier,
In that case you should implement your own parser. Something like what's done here:
http://www.jguru.com/faq/view.jsp?EID=480122
Searching on the internet I found there are several components for doing this but none of them is free:
http://www.sourcecodeonline.com/details ... arser.html
That's why I recommended using Dew Research's as MtxVec includes full TeeChart support.
Posted: Tue Dec 02, 2008 10:01 am
by 9350489
thank you very much
Didier