'ProgramMode:RUN
Menu "Use current _GraphY_1 ?","Yes",1,"No, let me type it",0
Lbl 0
"Type new _GraphY_1 (use X)"?->Str 1
Str 1->GraphY1
Lbl 1
"Lower Bound"?->A
"Upper Bound"?->C
GraphY1(A)->B
GraphY1(C)->D
ClrText
Locate 1,2,"("
Locate 2,2,A
Locate 10,2,","
Locate 11,2,B
Locate 20,2,")"
Locate 1,3,"("
Locate 2,3,C
Locate 10,3,","
Locate 11,3,D
Locate 20,3,")"
(D-B)/(C-A)->M
M*-1*A+B->I
Locate 1,4,"Slope M: "
Locate 11,4,M
Locate 1,5,"some c values in P,Q"
Solve(d/dx(GraphY1(X),X)-M=0,X,A,C)->P
Locate 1,6,P
(D-B)/(C-A)->M
(-)1*M*A+B->I
"M*X+I"->GraphY2
A->Xmin
C->Xmax
If M<0
Then 
GraphY1(A)->Ymax
GraphY1(C)->Ymin
Else 
GraphY1(C)->Ymax
GraphY1(A)->Ymin
IfEnd
Stop