Questions tagged [system-variables]
71 questions
21
votes
2 answers
Where can I permanently modify $Path?
I've quite forgotten: what file does one modify in order to add directories to $Path globally? Specifically, I want to include $UserBaseDirectory/ExtraPackges.
Or does one do it by means of modifying some setting in the OptionInspector (for Global…
murray
- 11,888
- 2
- 26
- 50
11
votes
4 answers
How to change the variables Qi's to Ri's in one or two steps
I was wondering if there is a command in Mathematica to change all the following Qi's to Ri's? For example, change Q1 to R1, Q2 to R2, etc.
Q1 a1 + Q2 a2 + Q3 a3 + Q4 a4 + Q5 a5 + Q6 a6 + Q7 a7 + Q8 a8 +
Q9 a9 + Q10 a10 + Q11 a11 + Q12 a12 + Q13…
math-visitor
- 319
- 2
- 8
5
votes
3 answers
Creating a variable from Reduce[] output in Mathematica
Say I have the following input:
Reduce[{t*c==50, t==5}]
the output:
t == 5. && c == 10.
Is there a way to create a variable x that gets assigned the value of c from the output without actually having to type x = 10?
Mardymar
- 219
- 2
- 5
4
votes
1 answer
Mathematica not seeing my environment/system variables
I'm trying to access my environment variables in Mathematica, but I get a Failed result every time. For example:
$ echo $USER
jlconlin
but in Mathematica I do:
Environment["User"]
(* $Failed *)
Is there a preference that I need to set? Is my…
jlconlin
- 247
- 2
- 7
4
votes
3 answers
variable K cannot be deleted
If a value is assigned to a variable that is named by capital K it cannot be deleted. This effect can be observed directly after start of the program.
Is this a bug?
granular_bastard
- 593
- 4
- 12
4
votes
2 answers
Solve says my system of equations has no solution
I got a system like this (just for example):
I need to get some of the variables expressed in a form like the following.
x == (z - z1) Tan[α1q - μ ] + x1
Let's say that x and σ are required. I write the following code:
eq1 := (x - x1) == (z - z1)…
crx
- 87
- 7
2
votes
0 answers
What is the purpose of the two variables Global`args and Global`dims
When opening the mma, I find that two variables Global`args and Global`dims have been defined. One can check them by running ?Global`* .
What is the purpose of the two variables?
When I load other packages, there is a warning "Symbol args appears…
user69086
- 21
- 1