For reference, when you use regression commands in a program rather than on the home screen, the stat variables a, b, r and r² are set, so you could do something like this:
Code: Prompt N
ln(L₂→L₄
L₂⁻¹→L₃
If (N=1
(L₂²-L₂(1)²)→L₅
If (N=0
(L₂-L₂(1))→L₅
LinReg(ax+b) L₁,L₅,Y₁
Disp "Slope",a
Disp "Y Intercept",b
Disp "r",r
Disp "r²",r²
(Where a,b,r and r² are the variables from the [VARS]→[Statistics...]→[EQ] menu)
However, if the last line of a program is value-returning, that value gets displayed, which is why when you put the LinReg command at the end of the program, you get everything displayed.
You don't need Then and End if your if statement only has 1 line. You don't need to close quotes and parentheses at the end of lines. I would recommend using L1 and L2 when using regression commands because they are the default, so if you use those, you can just say
Code: LinReg(ax+b)
instead of
LinReg(ax+b) L₁,L₂,Y₁
I didn't change that because I'm assuming this is part of a bigger program where those variables are already used. Also, your If statements could be done like this:
Code: If N
(L₂²-L₂(1)²)→L₅
If not(N
(L₂-L₂(1))→L₅
Since non-zero values evaluate to true, but in case you would want to add more formulas, I left that as-is. If you're just using N to determine what formula the user wants to use, I would recommend the menu() command, which will be a lot more intuitive and clean for users.
However, if you want to stick with the current Prompt, assuming N will only take either 1 or 0, if you want to be really fancy, you could do this:
Code: (L₂²-L₂(1)²)
can be factorized into:
(L₂-L₂(1))(L₂+L₂(1))
so using N to combine the two formulas, you get to replace this:
If N
(L₂²-L₂(1)²)→L₅
If not(N
(L₂-L₂(1))→L₅
with this:
(L₂-L₂(1))(not(N)+N(L₂+L₂(1→L₅
