Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2003
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2003

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Summation Problem w/ 5.0

  • To: mathgroup at smc.vnet.net
  • Subject: [mg43815] Re: Summation Problem w/ 5.0
  • From: andrea.knorr at engr.uconn.edu (Andrea)
  • Date: Tue, 7 Oct 2003 02:40:54 -0400 (EDT)
  • References: <blr1f1$3ge$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Bill Rowe <readnewscix at mail.earthlink.net> wrote in message news:<blr1f1$3ge$1 at smc.vnet.net>...
> On 10/4/03 at 2:05 AM, andrea.knorr at engr.uconn.edu (Andrea) wrote:
> 
> > Has anyone else had this problem with the new version?  I have created
> > multiple lists with multiple elements, and I am trying to sum all
> > elements of all lists.  As output I don't get a single value; instead
> > I get several numbers separated by a plus sign.  For example, instead
> > of Mathematica giving "2" as output, I get "1+1".  
> 
> I am using ver 5.0 under Max OSX version 10.2.8 and do not see this behavior. I or someone else here might be able to offer constructive suggestions if you post the code leading to this problem.
> 
> To reply via email subtract one hundred and nine


I posted code Saturday morning, but it has not been added, so I will
try again.  In my program I have created three lists, "virus",
"uninfected", and "infected" which are concentrations at a particular
time.  "vtime", "xtime", and "ytime" are the time points that
correspond to the given concentration.  The function "titer" solves
three differential equations that model a viral system.  minfcn is a
part of nonlinear regression.  The problem I am having occurs when I
evaluate minfcn, using the parameters published in a journal article,
at values above a particular element of "virus", "uninfected", and
"infected".  Here's the code:

titer[lambda_, beta_, d_, k_, a_, u_] :=
    
    Module[{soln, x, y, v, valueslist, xeval, yeval, veval}, 
      
      soln = NDSolve[{
            x'[t] == lambda - d x[t] - beta x[t] v[t],
            y'[t] == beta x[t] v[t] - a y[t],
            v'[t] == k y[t] - u v[t], 
            x[0] == 10^9, y[0] == 0, v[0] == 10^9},
          {x, y, v}, {t, 0, 2500}];
      
      xtiter = Evaluate[x[xtime] /. soln];
      ytiter = Evaluate[y[ytime] /. soln];
      vtiter = Evaluate[v[vtime] /. soln];
      
      values = Table[Flatten[{xtiter, ytiter, vtiter}, 1]];
      values
      ];				

calcs = titer[10^7, 5*10^-10, 0.1, 500, 0.5, 5];

minfcn[lambda_, beta_, d_, k_, a_, u_] :=
  
  Module[{i, j},
    
    diffsum = 
      Sum[10000*(uninfected[[i, 2]] - calcs[[1, i]])^2 + 
            10000*(infected[[i, 2]] - calcs[[2, i]])^2, {i, 
            Length[uninfected]}] + 
        Sum[(virus[[j, 2]] - calcs[[3, j]])^2, {j, Length[virus]}];
    diffsum
    ]

minfcn[10^7, 5*10^-10, 0.1, 500, 0.5, 5]

Here is the output:

(2.518473817923033*10^24 + 
    10000*(-1.80000521715242*10^7 + 20000)^2 + 
    10000*(-1.8*10^7 + 20000)^2 + 
    10000*(-1.*10^7 + 980000)^2 + 
    10000*(-9.99926182857273*10^6 + 980000)^2)

I need a single number to continue my calculations.

~Andrea


  • Prev by Date: Help with Nonlinear Fitting?
  • Next by Date: Re: Airy's Gi(x) function; asymptotic matching and asymptotic limits
  • Previous by thread: Re: Summation Problem w/ 5.0
  • Next by thread: Re: Re: Summation Problem w/ 5.0