# Can't understand the meaning of some symbols

1. ### shakgoku

29
1. The problem statement, all variables and given/known data
This is an extract from elements of mechanics by giovanni.
I'[m unable to understand the meaning of $$R^d$$ and $$C^\infty$$

http://flic.kr/p/9K8P7p

2. Relevant equations

3. The attempt at a solution

Last edited: May 20, 2011
2. ### tiny-tim

26,041
hi shakgoku!

Rd is the same as Rn

i assume "d" stands for "dimension"

and C is the space of functions which are differentiable "infinitely many" times

3. ### shakgoku

29
Hey tiny-tim!

Thank you , now everything in the page makes sense to me! :)