Mathematica says that a variable is not defined, yet it gives me a value
104468
Clear complains that a subscripted variable is not a symbol or a string?
116283
How to properly interpret a seemingly contradictory result in Mathematica?
19240
My attempt at value initialization is interpreted as a function declaration, and why doesn't A a(()); solve it?
110187
I get the warning "Undefined control sequence" with \mathbb
52916
Why am I getting "undefined reference to sqrt" error even though I include math.h header?
151869
What's the scope of a variable initialized in an if statement?
114227
Mathematica won't simplify multiplication by zero
18876
General::ivar is not a valid variable when plotting - what actually causes this and how to avoid it?
127924
How to deal with an error such as "Coefficients: 14 not defined because of singularities" in R?
110433
Locally declared variables can not be inspected
123022
Confusion with floating point numbers
10896
Missing $ inserted in maths mode
5320
What makes the mean of some distributions undefined?
140860
Variable substitution when integrating with Mathematica
146770
Why is $\frac{1}{\frac{1}{0}}$ undefined?
45665
CUDA FORTRAN: function gives different answer if I pass variable instead of number
16816
Why doesn't the example compile, aka how does (co-, contra-, and in-) variance work?