Show that an irrationally periodic function is also a constant function
100319
Functional equation with strange property about irrational numbers
85750
If $f(x)=\int_{x-1}^x f(s)ds$, is $f$ constant? Periodic?
17234
Show that a continuous function has a fixed point
142494
Functions $f(x)/g(x), g(x)/h(x),h(x)/f(x)$ are constant
158230
prove that a non constant periodic, continuous function has a "smallest period"
74245
Characterizing non-constant entire functions with modulus $1$ on the unit circle
41841
Function with limits only at irrational points
114245
What might I use to show that an entire function with positive real parts is constant?
727
Prove that any continuous integer-valued function of a real variable is constant.
26388
proof that function is constant
127953
Integral of periodic function over the length of the period is the same everywhere
146654
Real valued analytic function defined on a connected set is constant
8179
If $f$ is entire and $|f|\geq 1$, then show $f$ is constant.
152701
A question on periodicity of complex functions
35754
Is $f(x)=\sin(x^2)$ periodic?
54297
Is $f(x)=10$ a periodic function?
102075
A function continuous on all irrational points