how do i solve plot error

i faced this error in plotting pls help

i want to subs f=100.200,300 how do i do that?

[Walter Roberson]

Lots of undefined variables.

Define things before you use them. Like define w before you use it in H

[grace lim]

i still have error even after changing the bracket

[grace lim]

yes i hve defined it at the top,

but the f seems to be the problem

[Walter Roberson]

You have not defined w before you use it in H. You have not defined C or R. You have not defined f

[grace lim]

yes i have syms those symbols as im using symbols in this case

[Walter Roberson]

Suppose you have the code

A = 3
B = A * 4
A = 5

What is the value of B afterwards? Does B start evaluating to 20 on the basis that B is a formula in A and "should" update every time A updates? If so then consider

A = 3
B = A * 4
A = B + 1

If the variables remember their formulas then it follows that

A == B + 1
A == 4*A + 1
0 == 3*A + 1
A == -1/3
B == 4*A 
B == -4/3

So if variables remember their formulas and adjust as the defining variables change then it follows from the formulas that the relationship between the formulas requires that A = -1/3 and B = -4/3. But! We defined A = 3 remember! Deduction from the formulas as the variables update has arrived at a contradiction!

If we had done something like

 A = 3
 B = A - 1
 A = B - 1

then the two formula imply that B = B - 2 which implies 0 = - 2 (impossible) or implies B is infinite

Is this a sustainable interpretation of the meaning of what happens if you update a variable after it has been used? No.

And so when you define H in terms of w and then you change w, you should not be expecting H to suddenly change to the new definition of w.

You should be defining w (in terms of f) before you use w (in H)