Построение графиков функций y=f(x).

Program Grafiks;
Uses Graph,Crt;
Var
GraphDriver,GraphMode,Deltha:Integer;
X,Y,Xmax,Xmin,Ymax,Ymin:Real;
Xg,Yg,I,X0,Y0,XgMax,XgMin,YgMax,YgMin,DelthaY:Integer;
Grafik,C:Char;
SS:String;
Begin
ClrScr;
TextColor(White);
WriteLn(' Case grafik of');
WriteLn('  "1"  >> X');
WriteLn('  "2"  >> Sqr(X)');
WriteLn('  "3"  >> Abs(X)');
WriteLn('  "4"  >> 1/X');
WriteLn('  "5"  >> Sin(X)');
WriteLn('  "6"  >> Cos(X)');
WriteLn('  "7"  >> Sqrt(X)');
WriteLn('  "8"  >> Ln(X)');
WriteLn('  "9"  >> Tg(X)');
WriteLn('  "0"  >> Exp(X)');
WriteLn('  "a"  >> Exp(Sin(X))');
WriteLn('  "b"  >> Exp(Cos(X))');
WriteLn('  "c"  >> Abs(Sin(X))');
WriteLn('  "d"  >> Abs(Cos(X))');
WriteLn('  "e"  >> 1/Sin(X)');
WriteLn('  "f"  >> 1/Cos(X)');
WriteLn('  "g"  >> Abs(Ln(X))');
WriteLn('  "h"  >> Sin(Sqr(X))');
WriteLn('  "i"  >> Cos(Sqr(X))');
WriteLn('  "k"  >> Sin(Sqrt(X))');
WriteLn('  "l"  >> Cos(Sqrt(X))');
WriteLn('  "m"  >> Sqr(Sin(X))');
WriteLn('  "n"  >> Sqr(Cos(X))');
WriteLn('  "o"  >> Sin(1/X)');
 
Grafik:=ReadKey;
Write('  Deltha=');ReadLn(Deltha);
GraphDriver:=Detect;
InitGraph(GraphDriver,GraphMode,'bgi\');
SetBkColor(0);
SetColor(0);
Bar(0,0,GetMaxX,GetMaxY);
SetColor(LightGray);
Xg:=0;
While (Xg<=GetMaxX) Do Begin
Line(Xg,0,Xg,GetMaxY);
Xg:=Xg+10;
End;
Yg:=0;
While (Yg<=GetMaxY) Do Begin
Line(0,Yg,GetMaxX,Yg);
Yg:=Yg+10;
End;
SetColor(Black);
X0:=GetMaxX Div 2;
Y0:=GetMaxY Div 2;
Line(0,Y0,GetMaxX,Y0);(* X *)
Line(X0,0,X0,GetMaxX);(* Y *)
OutTextXY(X0+10,10,'Y');
OutTextXY(GetMaxX-10,Y0+10,'X');
Xg:=X0;i:=0;
While (Xg<GetMaxX) Do
Begin
SS:='';
Line(Xg,Y0+5,Xg,Y0-5);
Xg:=Xg+Deltha;
End;
Yg:=Y0;
While (Yg<GetMaxY) Do
Begin
Line(X0+5,Yg,X0-5,Yg);
Yg:=Yg+Deltha;
End;
Xg:=X0;
While (Xg>0) Do
Begin
Line(Xg,Y0+5,Xg,Y0-5);
Xg:=Xg-Deltha;
End;
Yg:=Y0;
While (Yg>0) Do
Begin
Line(X0+5,Yg,X0-5,Yg);
Yg:=Yg-Deltha;
End;
Xmin:=-1000;
X:=Xmin;
Xmax:=1000;
While (X<=Xmax) Do
Begin
Xg:=X0+Round(X);
Case Grafik of
'1':Y:=X;
'2':Y:=Deltha*Sqr(X/Deltha);
'3':Y:=Abs(X);
'4':Y:=Deltha*(1/(X/Deltha));
'5':Y:=Deltha*Sin(X/Deltha);
'6':Y:=Deltha*Cos(X/Deltha);
'7':Begin
If (X>=0) Then Y:=Deltha*Sqrt(X/Deltha) Else Y:=0 End;
'8':Begin
If (X>=0) Then Y:=Deltha*Ln(X/Deltha) Else Y:=0 End;
'9':Y:=(Deltha*Sin(X/Deltha))/(Deltha*Cos(X/Deltha));
'0':Y:=Deltha*Exp(X/Deltha);
'a':Y:=Deltha*Exp(Sin(X/Deltha));
'b':Y:=Deltha*Exp(Cos(X/Deltha));
'c':Y:=Deltha*Abs(Sin(X/Deltha));
'd':Y:=Deltha*Abs(Cos(X/Deltha));
'e':Y:=Deltha/Sin(X/Deltha);
'f':Y:=Deltha/Cos(X/Deltha);
'g':Begin
If (X>=0) Then Y:=Deltha*Abs(Ln(X/Deltha)) Else Y:=0 End;
'h':Y:=Deltha*Sin(Sqr(X/Deltha));
'i':Y:=Deltha*Cos(Sqr(X/Deltha));
'k':Y:=Deltha*Sin(Sqrt(Abs(X)/Deltha));
'l':Y:=Deltha*Cos(Sqrt(Abs(X)/Deltha));
'm':Y:=Deltha*Sqr(Sin(X/Deltha));
'n':Y:=Deltha*Sqr(Cos(X/Deltha));
'o':If (X<>0) Then Y:=Deltha*Sin(1/(X/Deltha)) Else Y:=0;
'p':Y:=Deltha*(Sin(Exp(Cos(X/Deltha))));
'q':Y:=Deltha*(Cos(Exp(Cos(X/Deltha))));
'r':Y:=Deltha*(Cos(Exp(Sin(Sqr(X/Deltha)))));
's':Y:=Deltha*(Sin(Exp(Cos(Sqr(X/Deltha)))));
't':Y:=Deltha*(Cos(Exp(Cos(Sqr(X/Deltha)))));
'u':Y:=Deltha*(Sin(Exp(Sin(Sqr(X/Deltha)))));
'v':Y:=Deltha*(Sin(Exp(Sin(Sqrt(Abs(X)/Deltha)))));
'w':Y:=Deltha*(Sin(Exp(Cos(Sqrt(Abs(X)/Deltha)))));
'x':Y:=Deltha*(Cos(X/Deltha)*Sin(1/(X/Deltha))/Cos(1/(X/Deltha)));
'y':Y:=Deltha*(Exp(Sin(X/Deltha)*Sin(1/(X/Deltha))));
'z':Y:=Deltha*Sqr(Exp(Sin(X/Deltha)*Sin(1/Sqrt(Abs(X)/Deltha))))*Cos(X/Deltha);
' ':Y:=Deltha*Sin(1/Sqrt(Abs(X)/Deltha))*Sin(Sqr(X/Deltha));
Else Y:=X;
End;
Yg:=Y0-Round(Y);
If (Yg<>Y0) Then PutPixel(Xg,Yg,Blue);
X:=X+0.0009;
End;
ReadLn;
CloseGraph;
End.