Add the option to specify the number of coefficients

[ufechner7]

I currently use this code:

f = Fun(discrete_signal, Chebyshev(Interval(t1[1],t1[end])))
f1 = Fun(Chebyshev(Interval(t1[1],t1[end])), coefficients(f)[1:5])

to approximate the function discrete_signal with a Chebyshev function using 5 coefficients. That is a waste of cpu cycles, first to calculate thousends of coefficients just to through most of them away. Please add an option to specify the max number of coefficients.

[dlfivefifty]

Fun(f, sp, n)

[ufechner7]

Nice!

Is this documented anywhere?