For questions relating to assignments to symbols, patterns, or expressions.

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10
votes
3answers
303 views

Why does ++++x return an increment of 2 when the value of x is only incremented by 1?

This line returns 3: x = 1; ++++x However, the value of x after the increment is only ...
8
votes
3answers
275 views

How to write a function-defining function which stores the function arguments in a stack?

I have a function-defining function SetAttributes[DefFn, HoldAll]; DefFn[f_[args___], body_] := f[args] := body; I am trying to modify this function to record ...
14
votes
1answer
229 views

How to make a function like Set, but with a Block construct for the pattern names

How can we define a function that works like f[x_]=ComputeSomething[x] and treats x as a variable that does not have a value? ...
1
vote
1answer
151 views

Differentiation w/o assiging concrete values

v = Subscript[v, 0]*Sin[(Pi*S)/Subscript[S, 0]]; a = dv/ds v; a = D[v, s] returns ...
20
votes
1answer
510 views

How do you set attributes on SubValues?

SubValues, as discussed in a previous question, are declared as follows ...
19
votes
5answers
453 views

Reassign values to symbols

I've got a situation where I have, say 4 symbols, a, b, c and ...
83
votes
2answers
3k views

What is the distinction between DownValues, UpValues, SubValues, and OwnValues?

When reading through the documentation, you often encounter the phrases DownValues, UpValues, ...
16
votes
4answers
654 views

How can I randomly generate a unique, unused symbol?

In a previous question on collecting terms for a multivariable polynomial, I answered with a solution that required a unused symbol to be used for a temporary substitution and back substitution. It ...
15
votes
2answers
181 views

Clearing a specific definition

Consider the case where a symbol has multiple definitions attached to it, a /: Subscript[a,2] := 1 a[b_] := 2 a[b_, c_] := 3 How does one clear (/unset/remove) ...