# LTSpice "Unknown parameter "\""

I am trying to simulate an electrical model (Mason Model) of piezoelectric system in LTSpice. So, I use parameters and formulas to evaluate the value of the passive elements in my circuit.

I use the following eq. for one of my capacitor:

C = {Zo}\{cos({Tou}*{t})}


which returns an error saying:

Error on line 9 : c3 p001 n007  63262.1256016315 \ 0.876872546720567
Unknown parameter "\"


I also use 1/{f} for calculating the on time of my pulse signal but that seems to work just fine. Am I missing to define a library?

• already tried {1/f}? Apr 25, 2019 at 23:25
• To extend a bit on @Unknown123's comment, why would you use \ after trying the normal /? Apr 26, 2019 at 13:37
• @Unknown123 1/{f} or {1/f} doesn't show an error but its the expression from C = {Zo}\{cos({Tou}*{t})} is the problem
– Akki
Apr 30, 2019 at 15:31
• @aconcernedcitizen results: Error on line 9 : c3 p001 n007 63262.1256016315 / 0.876872546720567 Unknown parameter "/" Error on line 9 : c3 p001 n007 63262.1256016315  0.876872546720567 Unknown parameter ""
– Akki
Apr 30, 2019 at 15:32
• @Akki Pardon for my indirect explanation. That's not my point actually. I mean you should know when you should wrap all of the equation using curly brackets and when you should not. Read here: .Param and Curly Brackets May 1, 2019 at 4:29

Change your \ to a / if you want to do division.

As far as I know, \ has no meaning in LTSpice, so it's not surprising it gives an error message about something being "unknown" when you use this symbol.

Edit

Based on comments, the actual problem is that the expression must be surrounded by { and }.

• Yes, tried changing the symbols. Still the same error ' Unknown parameter "/" '
– Akki
Apr 30, 2019 at 15:27
• @Akki, did you try wrapping the whole thing in { and }`? Apr 30, 2019 at 15:39
• Yes, That worked!
– Akki
Apr 30, 2019 at 15:55