Re: Forgets Variables?

*To*: mathgroup at smc.vnet.net*Subject*: [mg97237] Re: Forgets Variables?*From*: Ktota <NuKtoBi at gmail.com>*Date*: Mon, 9 Mar 2009 01:02:58 -0500 (EST)*References*: <200903070738.CAA16926@smc.vnet.net> <gp0830$l48$1@smc.vnet.net>

Thank you for your help Raffy and Bob, i'll try your suggestions and report here again. This model evolved over time.. i think i will have also to spend to optimize it as Bob suggests.. his suggestions are very nice... i'm busy learning Mathematica it seems to be a very helpfull tool ;). Kind Regards, Ktota On 8 Mrz., 10:53, DrMajorBob <btre... at austin.rr.com> wrote: > I can't get the first statement to execute (in the time I'm willing to = > wait). If you gave us the values of maxX, eqTime, v, lifetime27SA, et > cetera, we'd waste a lot less time guessing what your problem might be. > > If you want help, ALWAYS start us off where you are. Don't make us > flounder around where you've already been. Because, of course, why should= > we? > > That said, I'd start by simplifying until the code is understandable, at = > which point the error will reveal itself. For instance, this: > > If[v*(tsum - lifetime35S - eqTime) < 4000, > v*(tsum - lifetime35S - eqTime), 4000] > > is equivalent to the simpler (and faster) > > Min[v*(tsum - lifetime35S - eqTime), 4000] > > Similarly, this expression: > > If[v*(tsum - eqTime) < 4000, Max[v*(tsum - eqTime), 0], 4000] > > is equivalent to > > Max[0, Min[v*(tsum - eqTime), 4000]] > > Next, it's easy to see that > > If[v*(tsum2 - eqTime) < 4000, > Sum[Max[v*(tsum - eqTime), 0], {tsum, tsum2 - lifetime27SANTC + 1, > tsum2}], > Sum[Max[0, Min[v*(tsum - eqTime), 4000]], {tsum, > tsum2 - lifetime27SANTC + 1, tsum2}]] > > is equivalent to > > Clear[q] > q[ts_] := v*(ts - eqTime); > If[q@tsum2 < 4000, > Sum[Max[q@tsum, 0], {tsum, tsum2 - lifetime27SANTC + 1, tsum2}], > Sum[Max[0, Min[q@tsum, 4000]], {tsum, tsum2 - lifetime27SANTC + 1, > tsum2}]] > > and that's equivalent to (since the Sums have the same limits): > > Clear[q] > q[ts_] := v*(ts - eqTime); > Sum[If[q@tsum2 < 4000, Max[q@tsum, 0], > Max[0, Min[q@tsum, 4000]]], {tsum, tsum2 - lifetime27SANTC + 1, > tsum2}] > > Similarly, the first If statement: > > If[v*(tsum2 - lifetime35S - eqTime) < 4000, > Sum[Max[v*(tsum - lifetime35S - eqTime), 0], {tsum, > tsum2 - lifetime27SA + 1, tsum2}], > Sum[Min[v*(tsum - lifetime35S - eqTime), 4000], {tsum, > tsum2 - lifetime27SA + 1, tsum2}]] > > is equivalent to > > Clear[q] > q[ts_] := v*(ts - lifetime35S - eqTime); > Sum[If[q@tsum2 < 4000, Max[q@tsum, 0], Min[q@tsum, 4000]], {tsum, > tsum2 - lifetime27SA + 1, tsum2}] > > Combining both tricks into one reduces the original expression to: > > Clear[q] > q[life_][ts_] := v (ts - life - eqTime) > callNormValue = > 60/maxX Sum[ > Sum[If[q[lifetime35S]@tsum2 < 4000, Max[q[lifetime35S]@tsum, 0= ], > Min[q[lifetime35S]@tsum, 4000]], {tsum, > tsum2 - lifetime27SA + 1, tsum2}]*(1 - P) + > Sum[If[q[0]@tsum2 < 4000, Max[q[0]@tsum, 0], > Max[0, Min[q[0]@tsum, 4000]]], {tsum, > tsum2 - lifetime27SANTC + 1, tsum2}]*P, {tsum2, 60, t2= , 60}]; > > That still won't evaluate without values for all the parameters, but > you're the only one that knows those, or even knows what ranges they migh= t > lie in. > > One trick you MIGHT pull, however, is this: > > Clear[q] > q[life_][ts_] := v (ts - life - eqTime) > callNormValue = > 60/maxX sum[ > sum[If[q[lifetime35S]@tsum2 < 4000, Max[q[lifetime35S]@tsum, 0= ], > Min[q[lifetime35S]@tsum, 4000]], {tsum, > tsum2 - lifetime27SA + 1, tsum2}]*(1 - P) + > sum[If[q[0]@tsum2 < 4000, Max[q[0]@tsum, 0], > Max[0, Min[q[0]@tsum, 4000]]], {tsum, > tsum2 - lifetime27SANTC + 1, tsum2}]*P, {tsum2, 60, t2= , 60}]; > > (Now the statement executes.) > > callNormValue /. {lifetime35S -> 17, P -> 0.7, t2 -> maxX, sum -> Sum} > > (The other parameters still need values, but those could be added to the = > rule list.) > > Bobby > > > > > > On Sat, 07 Mar 2009 01:38:46 -0600, Ktota <NuKt... at gmail.com> wrote: > > Hi there, > > > i have the following procedure: > > > callNormValue = (Sum[ > > If[v*(tsum2 - lifetime35S - eqTime) < 4000, > > Sum[Max[v*(tsum - lifetime35S - eqTime), 0], {tsum, > > tsum2 - lifetime27SA + 1, tsum2, 1}], > > Sum[If[v*(tsum - lifetime35S - eqTime) < 4000, > > v*(tsum - lifetime35S - eqTime), 4000], {tsum, > > tsum2 - lifetime27SA + 1, tsum2, 1}]]*(1 - P) + > > If[v*(tsum2 - eqTime) < 4000, > > Sum[Max[v*(tsum - eqTime), 0], {tsum, > > tsum2 - lifetime27SANTC + 1, tsum2, 1}], > > Sum[If[v*(tsum - eqTime) < 4000, Max[v*(tsum - eqTime),= 0], > > 4000], {tsum, tsum2 - lifetime27SANTC + 1, tsum2, 1= }]]* > > P, {tsum2, 60, t2, 60}])/(maxX/60); > > > i call it with: > > callNormValue /. {lifetime35S -> 17, P -> 0.7, t2 -> maxX} > > > it gives me a proper result, but as soon i change t2 to maxX in the > > first expression (where i do the sums) it doesn't evaluate the the > > procedure anymore (maxX has a global value already set). I have > > actually quite a lot of trouble to hand over values to this > > procedure.. and i have no idea why it doesn't work. > > > (for except lifetime35S,P and t2 all the variables have a set value) > > > thank you, > > > Ktota > > -- > DrMajor... at bigfoot.com

**References**:**Forgets Variables?***From:*Ktota <NuKtoBi@gmail.com>