# Recursion depth of 1024 exceeded during evaluation [closed]

This is my very first day using Mathematica, so please forgive me my complete ignorance...

I fear that this might be one of those questions that gets rejected for being "easily found in the documentation"... Nevertheless, searching hard and long through the documentation all that I may, I completely fail to find an answer to my - no doubt obvious - mistake...

I tried to define a function x[t_] and a function y[t_], both as it seems successfully...

I then tried to put them together in a complex valued function f[t_], which I believed to be an operation that could not possibly go wrong...

However to my surprise I keep getting a "Recursion depth of 1024 exceeded during evaluation of f[0]" error...

I really fail to see where this "recursion" could possibly come from...

Could anyone please put this noobie on the right track?

a = 2
(* 2 *)

T = 2^(3/2)
(* 2 Sqrt[2] *)

x[t_] = a Cos[2 Pi t/T] - Cos[2 Pi t]
(* -Cos[2 π t] + 2 Cos[(π t)/Sqrt[2]] *)

y[t_] = a Sin[2 Pi t/T] - Sin[2 Pi t]
(* -Sin[2 π t] + 2 Sin[(π t)/Sqrt[2]] *)

f[t_] = x[t] + I y[t]

During evaluation of In[112]:= $RecursionLimit::reclim2: Recursion depth of 1024 exceeded during evaluation of f[0]. >> During evaluation of In[112]:= Set::write: Tag Hold in Hold[f[0]] is Protected. >> (* -Cos[2 π t] + 2 Cos[(π t)/Sqrt[2]] + I (-Sin[2 π t] + 2 Sin[(π t)/Sqrt[2]]) *) f[0] During evaluation of In[113]:=$RecursionLimit::reclim2: Recursion depth of 1024 exceeded during evaluation of f[0]. >>

(* Hold[f[0]] *)


## closed as off-topic by ciao, Dr. belisarius, bbgodfrey, Kuba♦, Karsten 7.Apr 2 '15 at 9:16

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question arises due to a simple mistake such as a trivial syntax error, incorrect capitalization, spelling mistake, or other typographical error and is unlikely to help any future visitors, or else it is easily found in the documentation." – ciao, Dr. belisarius, bbgodfrey, Karsten 7.
If this question can be reworded to fit the rules in the help center, please edit the question.

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• I think you want to do your assignments with f[t_] := (note the extra colon, "delayed assignment"). I don't see the recursion here either, but if you have done a bunch of trial-and-errors, then you may have some definitions left over that cause the recurrence. Simply quit the kernel (or mathematica) and start again. – Eric Brown Apr 2 '15 at 0:17

So much wrong there...

a = 2;
tx = 2^(3/2);
x[t_] := a Cos[2 Pi t/tx] - Cos[2 Pi t];
y[t_] := a Sin[2 Pi t/tx] - Sin[2 Pi t];
f[t_] := x[t] + I y[t];

f[20]

(* -1 + 2 Cos[10 Sqrt[2] π] + 2 I Sin[10 Sqrt[2] π] *)


Don't use uppercase initials for your symbols - you might clash with built-ins.

Don't use some external user-defined global symbol inside a definition in the manner you have unless there's a good reason to do so (I left that as is, but it's bad practice).

Read the documentation, learn the difference between Set (=) and SetDelayed (:=).

Read What are the most common pitfalls awaiting new users? on this very site. Great resource for new users.

Go through the tutorials in the Mathematica documentation. Very worthwhile.

• Thanks, that fixed it. And thanks for the tips! – tasso Apr 2 '15 at 19:13