Function: intfuncinit
Section: sums
C-Name: intfuncinit0
Prototype: V=GGED0,L,D0,L,p
Help: intfuncinit(X=a,b,expr,{flag=0},{m=0}): initialize tables for integrations
 from a to b using a weight expr(X). Essential for integral transforms such
 as intmellininv, intlaplaceinv and intfourier, since it avoids recomputing
 all the time the same quantities. Must then be used with intmellininvshort
 (for intmellininv) and directly with intnum and not with the corresponding
 integral transforms for the others. See help for intnum for coding of a
 and b, and m is as in intnuminit. If flag is nonzero, assumes that
 expr(-X)=conj(expr(X)), which is twice faster.
Wrapper: (,,G)
Description:
  (gen,gen,gen,?small,?small):gen:prec intfuncinit(${3 cookie}, ${3 wrapper}, $1, $2, $4, $5, prec)
Doc: initialize tables for use with integral transforms such as \kbd{intmellininv},
 etc., where $a$ and $b$ are coded as in \kbd{intnum}, $\var{expr}$ is the
 function $s(X)$ to which the integral transform is to be applied (which will
 multiply the weights of integration) and $m$ is as in \kbd{intnuminit}. If
 $\fl$ is nonzero, assumes that $s(-X)=\overline{s(X)}$, which makes the
 computation twice as fast. See \kbd{intmellininvshort} for examples of the
 use of this function, which is particularly useful when the function $s(X)$
 is lengthy to compute, such as a gamma product.

 \synt{intfuncinit}{void *E, GEN (*eval)(void*,GEN), GEN a,GEN b,long m, long
 flag, long prec}. Note that the order of $m$ and $\fl$ are reversed compared
 to the \kbd{GP} syntax.
