# What does this notation mean?

u := -v

specifically the " := "

Here is the context. When f, g are suitably regular functions on R we can use the change of variable u:=-v etc..

I should add that I came across this in a Fourier Transform book..

Thanks!

Last edited:

Office_Shredder
Staff Emeritus
Gold Member
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It usually means 'defined to be'.

So in this context, we know what v is, and we want to define u as a new variable. So you write u := -v to let the reader know u is being defined as -v (where v has been defined previously).

Ah... well that makes sense
thank you very much.

CRGreathouse
Homework Helper
What, you haven't learned all half-dozen (dozen?) different symbols for "defined as" yet? :p

the program MathCad uses the ":=" to define things like variables and functions. perhaps you saw a document made with mathcad?