trigonometric functions

[Sara Costa]

Dear sir/madam

I am doing my PhD in Mathematics and I am starting to use gmp because I
need to compute some thing with a lot of precision. What I have to do is
to iterate many many times a map, usually a multidimensional map. The
trouble, after reading the manual, I find is that in the the
trigonometric fuctions, or at least one of them (e.g. the cosinus of a
number) is not in the library. The hiperbolic trigonometric functions
are not a problem because they are defined in terms of the exponential
of the number. The same happens with the logarith, but about this
particular I have to read carefully the manual, because if there is any
way to compute it in basis 2, I can coumpute it is basis "e" using just
the relation between the two logarithms

My question is: Is there any good way to compute them using as much
precision as I need?

Thank you in advance.

Yours sincerelly

Sara Costa Romero

PS: I'm very sorry about my poor English.