Oh God, the nay-saying. Take all these "I dunno"'s elsewhere, and don't convert them to "it can't be done"'s. It's that simple.
:ClrHome
:For(S,0,1
:"(→Str1
:For(T,0,1
:Repeat K=105
:Output(S+1,1,Str1+sub(",)",T+1,2-T)+"<12 spaces>
:Repeat Ans or K=45 or 2>abs(5-abs(5-abs(K-83
:getKey→K
:Ans>E2
:End
:round(13fPart(13‾¹(K-Ans
:If Ans and 7T+7≠length(Str1
:Str1+sub("1234567890.‾",Ans,1→Str1
:If K=45
:DelVar T"(→Str1
:End
:If not(T
:Str1+",→Str1
:End
:expr("{"+sub(Str1,2,length(Str1)-1→L2
:If not(S
:Ans→L1
:End
:ClrHome
:Disp L1,L2
L1 and L2 are stored rather than A/B/X/Y. This supports decimal points and negation, and is limited to up to 6 characters per x, and up to 12-length(x) characters per y. CLEAR erases progress for the entire coordinate. A syntax error and 2:Goto will divert to the homescreen instead of the editor. Really though, if you consider the sequence of key presses for these inputs, it's identical to the following:
:Input "x1=",X
:Input "y1=",Y
:Input "x2=",A
:Input "y2=",B
Ask yourself whether bells and whistles is worth hindering efforts to solve the problem.
(account deleted)
