Re: Logical expressions help! (newbie)

Hi Nektarios,

Suppose you have a mathematical expression valid if 0,5 < x < 2
where x is a real number.
Suppose again that you have a second mathematical expression valid if 0<x<1,5.

Now let the user enter x in a Edit box.

If user enters x=1 the program should inform him that both mathematical expressions works for him and let him choose which mathematical expression works for him.

I think i understand that part.

The mathematical expressions calculate "Nusselt number" , a number to calculate heat transfer phenomena. The mathematical expressions do NOT find the same Nusselt number. A 10% deviation is present.
Example
Nusselt1=2*x+3
Nusselt2=5*x-1

I think i don't understand that part.
The expressions mentioned above check if a number is in two
ranges. They don't calculate anything. How do you get from
0,5 < x < 2 and 0<x<1,5 to 2*x+3 and 5*x-1 ?


How can i make the program to find out that both mathematical expressions are valid ( "if then else" won't work in case of x=1 ) and inform the user about that ?


procedure Button1Click(Sender:Tobject);

var
Valid1,Valid2:Boolean;
x:extended;
begin
x:=StrToFloat(Edit1.text);
Valid1:=(0.5<x) and (x<2);
Valid2:=(0<x) and (x<1.5);
If Valid1 and Valid2 then ShowMessage('Both are valid')
else if Valid1 then ShowMessage('Expression 1 is valid)
else ShowMessage('Expression 2 is valid);
end;

After that, the program should present the two results in the same form.

What results? In what form?




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