MATLAB: Help debugging a symbolic expression error

syms

I'm trying to create a symbolic expression but don't fully understand the error I get. Code and error below.
syms l t b
f(l,t,b)=l((t/b)-(sin((2*pi*t)/b)/(2*pi)));
And the error:
Error using sym/subsindex (line 737)
Invalid indexing or function definition. When defining a function, ensure that the arguments are symbolic
variables and the body of the function is a SYM expression. When indexing, the input must be numeric, logical,
or ':'.
Error in sym/subsref (line 776)
            R_tilde = builtin('subsref',L_tilde,Idx);
I've tried making smaller expressions with syms variables and constants to eliminate the possibility that constants can't be used.

Best Answer

You’re missing a multiplication operator. MATLAB does not recognise implicit multiplication.
syms l t b
f(l,t,b) = l*((t/b)-(sin((2*pi*t)/b)/(2*pi)));
            ↑ ← INSERT ‘*’ HERE
That runs without error.
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