Re: How to express continued sum?

*To*: mathgroup at smc.vnet.net*Subject*: [mg73456] Re: How to express continued sum?*From*: "dimitris" <dimmechan at yahoo.com>*Date*: Sat, 17 Feb 2007 05:01:31 -0500 (EST)*References*: <er3hbm$f9e$1@smc.vnet.net>

Is Sum[f[x, y, z], {z, 0, 20}, {y, 0, 20}, {x, 0, 20}] what do you want? Information@Sum "Sum[f, {i, imax}] evaluates the sum of the expressions f as evaluated for each i from 1 to imax. Sum[f, {i, imin, imax}] starts with i = imin. Sum[f, {i, imin, imax, di}] uses steps di. Sum[f, {i, imin, imax}, {j, jmin, jmax}, ... ] evaluates a sum over multiple indices." Attributes[Sum] = {HoldAll, Protected, ReadProtected} Note also the presence of NSum Information@NSum "NSum[f, {i, imin, imax}] gives a numerical approximation to the sum of the expressions f as evaluated for each i from imin to \ imax. NSum[f, {i, imin, imax, di}] uses a step di in the sum." Attributes[NSum] = {HoldAll, Protected} Options[NSum] = {AccuracyGoal -> Infinity, Compiled -> True, EvaluationMonitor -> None, Method -> Automatic, NSumExtraTerms -> 12, NSumTerms -> 15, PrecisionGoal -> Automatic, VerifyConvergence -> True, WorkingPrecision -> MachinePrecision, WynnDegree -> 1} By the way what language is this: sigma(x=0..20)sigma(y=0..20)sigma(z=0..20)f(x,y,z) ??? Dimitris =CF/=C7 oicqgogogo at sina.com =DD=E3=F1=E1=F8=E5: > I want to know how to get the continued sum expression by mathematica? > Such > as: > sigma(x=0..20)sigma(y=0..20)sigma(z=0..20)f(x,y,z) > > Thanks!