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program RPNThing;
{
$ id: $
Copyright (c) 2000 by Marco van de Voort(marco@freepascal.org)
member of the Free Pascal development team
See the file COPYING.FPC, included in this distribution,
for details about the copyright. (LGPL)
Much too simplistic program to test some basic features of Symbolic unit.
It is the very rough skeleton of a symbolic RPN calculator like a HP48.
Since there are no exception conditions in the parser or evaluator,
please enter valid expressions.
Don't use 5E6 notation, it is not implemented yet. You can enter
symbolic expressions using x, integer constants and half the math
unit's function.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
}
{$ifdef FPC}
{$Mode ObjFpc}
{$endif}
Uses Symbolic,Crt;
function GetKey:char;
begin
repeat
while keypressed DO ;
result:=ReadKey;
if result=#0 then {Make sure control codes are skipped apropiately}
begin
result:=readKey;
result:=#0;
end;
until result IN ['X','x','O','o','q','Q',' ','+','-','*','/','^','e','E','d','D','T','t'];
end;
VAR Stack : array[0..100] of TExpression;
I,StackPtr : Integer;
InputC : Char;
S : String;
Flag : Boolean;
Procedure Redraw;
var I : Integer;
begin
for I:=1 to 20 DO
begin
GotoXY(1,I);
Write(' ':79);
GotoXY(1,I);
IF (StackPtr>(20-I)) then
begin
IF NOT Assigned(stack[20-I]) then
begin
gotoXY(1,1); write(' ':50);
gotoxy(1,1); writeln(I,' ',20-I);
Writeln(stackptr);
HALT;
end;
Writeln(stack[StackPtr-(21-I)].InfixExpr);
end
else
write('-');
end;
GotoXY(1,21);
Write(' ':80);
end;
begin
Writeln(' + - / * ^ : perform the RPN operation');
Writeln(' [space],'#39' : get a "prompt" to input a number or infix expression');
Writeln(' E,e : Try to simplify/evaluate the expression. ');
Writeln(' For now this is restricted to constant values only');
Writeln(' D,d : Drop 1 value from the stack');
Writeln(' Q,q : By pressing this key you agree this program is great');
Writeln(' O,o : Derive the expression with respect to X');
Writeln(' T,t : Taylor polynomal. Also with respect to X, and to 2nd ');
writeln(' stacklevel degree');
Writeln;
Writeln('Press enter to start calculating');
ReadLn;
ClrScr;
StackPtr:=0;
repeat
InputC:=GetKey;
Case InputC OF
'+','-','*','/','^' : if stackPtr>1 then
begin
Dec(StackPtr);
case InputC of {Double case is ugly but short}
'+' : Stack[StackPtr-1].AddTo(Stack[StackPtr]);
'-' : Stack[StackPtr-1].SubFrom(Stack[StackPtr]);
'*' : Stack[StackPtr-1].Times(Stack[StackPtr]);
'/' : Stack[StackPtr-1].DivBy(Stack[StackPtr]);
'^' : Stack[StackPtr-1].RaiseTo(Stack[StackPtr]);
end;
Stack[StackPtr].free;
Redraw;
end;
'E','e' : If Stackptr>0 then
begin
Stack[StackPtr-1].SimplifyConstants;
Redraw;
end;
'T','t' : If StackPtr>1 then {Stackptr-1=function. Stackptr-2=degree
x is assumed, and x0 is substed}
begin
Flag:=True;
Try
i:=Stack[StackPtr-2].ValueAsInteger;
except
on ENotInt do
begin
GotoXY(1,1);
WritelN('This constant doesn''t evaluate to an integer');
Flag:=False;
end;
end;
If I<0 then
begin
GotoXY(1,1);
WritelN('I never heard of negative terms in a Taylor polynomal');
end
else
If Flag then
begin
Stack[StackPtr-2].Free;
Stack[StackPtr-2]:=Stack[StackPtr-1];
Stack[StackPtr-1]:=Stack[StackPtr-2].Taylor(I,'X','0.0');
Redraw;
end;
end;
'O','o' : if StackPtr>0 then
begin
Stack[StackPtr]:=Stack[StackPtr-1].Derive('X');
Inc(StackPtr);
Redraw;
end;
'D','d' : If StackPtr>0 Then
begin
Stack[StackPtr-1].free;
Dec(StackPtr);
Redraw;
end;
' ',#39 : If Stackptr<100 then
begin
GotoXY(1,1); Writeln(' ':60);
gotoxy(1,1); write('Enter expr. : '); readln(s);
s:=upcase(S);
stack[StackPtr]:=TExpression.Create(S);
Stack[StackPtr].Simplificationlevel:=2; {Don't add reals to integer. Only evaluates
(integer op integer) and (real op real) and
function(real)}
Inc(Stackptr);
Redraw;
end;
'X','x' : begin
ClrScr;
Writeln(stdout,stack[StackPtr-1].InfixExpr);
Writeln;
Writeln(stdout,stack[StackPtr-1].RPNExpr);
inputC:='q';
end;
end;
until (InputC IN ['q','Q']);
If StackPtr>0 THEN
For I:=0 To StackPtr-1 Do
Stack[I].Free;
end.
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