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MathGroup Archive 2011

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problem while solving equations

  • To: mathgroup at smc.vnet.net
  • Subject: [mg122238] problem while solving equations
  • From: Maria Davis <arbiadr at gmail.com>
  • Date: Sat, 22 Oct 2011 06:05:38 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

Hi

I want to solve a system of equations for the variable "system".
Here is the content of the file containing equations to solve:

system ->(l * h) / (l + h)
a -> (x * g) / (x + g)
c -> (y * e) / (y + e)
e->(prod*q)/(prod+q)
g->(prod*q)/(prod+q)
h->(cons * c * a)/(cons + c + a)
q -> (n * o) / (n + o)
o ->1
n -> 1
l -> 1

Mathematica code source that I use is:
eqns = ToExpression[StringReplace[#, "." -> "\[Bullet]"]] & /@
ReadList["C:\equation.txt",Record];
rules = Flatten[{eqns, Min[x_ + y_, x_ + z_] -> x + Min[y, z], Max[x_
+ y_, x_ + z_] -> x + Max[y, z],
    Min[x_, x_ + z_] -> x + Min[0, z], Max[x_, x_ + z_] -> x + z ,
Max[x_, 0] -> x , Min[x_, infinity] -> x}];
system -> (system //. rules)

I obtained the expression of system using the other variables. In
order to have the numeric value of "system". I write this code:

props = ToExpression[StringReplace[#, "." -> "\[Bullet]"]] & /@
ReadList["C:\values.txt", Record];
system //. props

the file values contains:
c-> 1.5
p-> 2
y->3
x-> 2.6

But I don't obtain any result.
Can you please help me.



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