Convert s(exp,scope) to sum of exps

Description

This function converts the summation to sum and evaluates it.
s(exp[i],{i,1,3}) -> exp[1]+exp[2]+exp[3]

Usage

sum2sum(sexp, values = NULL, eval = 1, debug = 0)

Arguments

Details

For each summation found, replace it by its expansion as Sum. The replacement proceeds from the bottom to top levels.

Examples

sum2sum( "s(s(a[i,j],{i,1,ni}),{j,1,nj})", values="ni=2; nj=3")
sum2sum( "s(s(a[i,j],{i,from,to}),{j,1,nj})"
        , values="from=2; to=4; nj=3")

# unevaluated form
sexp <- "s( a[i], {i,1,2} )"
sum2sum( sexp, eval=1 )
ss <- sum2sum( sexp, eval=0 ) |> printm()
eval(parse(text=ss)[[1]])

# unevaluated form (Cannot be evaluated if the summations are nested.)
sexp <- "s( a[i]*s(b[i,j], {j,1,2}), {i,1,2} )"
sum2sum( sexp, eval=1 )
ss <- sum2sum( sexp, eval=0 ) |> printm()
# eval(parse(text=ss)[[1]])