Function: prodeuler
Section: sums
C-Name: prodeuler0
Prototype: V=GGEp
Help: prodeuler(X=a,b,expr): Euler product (X runs over the primes between a
 and b) of real or complex expression.
Doc: product of expression \var{expr},
 initialized at 1. (i.e.~to a \emph{real} number equal to 1 to the current
 \kbd{realprecision}), the formal parameter $X$ ranging over the prime numbers
 between $a$ and $b$.\sidx{Euler product}

 \synt{prodeuler}{void *E, GEN (*eval)(void*,GEN), GEN a,GEN b, long prec}.
