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My problem when solving a system of equations

• To: mathgroup at smc.vnet.net
• Subject: [mg78047] My problem when solving a system of equations
• From: loveinla at gmail.com
• Date: Thu, 21 Jun 2007 06:47:06 -0400 (EDT)

Hi, guys,

I was trying to solve a system of nonlinear equations. However,
whenever I run it, Mathematica always returns:
" ReplaceAll::reps: {-0.04\(-24 + 5\pA)\((25 - 4\p1)\(-2 + p1) - (24 -
\
5\pA)\(-3 + pA) + (-3 - disA + pA)\(24 - 5\(-disA + pA))) + 0.4\(\
\[LeftSkeleton]1\[RightSkeleton])\(\[LeftSkeleton]1\[RightSkeleton])
== 0, \
\[LeftSkeleton]3\[RightSkeleton]} is neither a list of replacement
rules nor \
a valid dispatch table, and so cannot be used for replacing. "

I don't know what this means and how to deal with it.

Below is my code for your reference:

a = 24;
b = 5;
c = 25;
d = 4;
cA = 3;
cB = 2;
t = 5;
alpha = 0;
bta = 0.6;
NB = NSolve[{-d(p - cB) + c - d*p == (p - cB)(c - d*p)^2/t}, {p}];
SNB = DeleteCases[NB, {p -> _Complex}]
B = NSolve[{(alpha + (1 - alpha - bta)*(0.5 - ((d/
          2)*(p1^2 - p2^2) - c*(p1 - p2))/(2t) - ((b/2)*((
      pA - disA)^2 - pA^2) + a*disA)/(2t)))*(a - b*pA - b*(pA -
    cA)) - (1 - alpha - bta)*((p1 - cB)*(c - d*
    p1) + (pA - disA - cA)*(a - b*(pA -
                   disA)) - (pA - cA)*(a - b*pA))*(-(
                    a - b*pA)/(
                        2t)) == 0, (1 - alpha - bta)*((a - b*(pA -
disA) -
                               b(pA - disA - cA))*(0.5 + ((d/2)*(
                        p1^2 - p2^2) - c*(
                                p1 - p2))/(2t) + ((b/2)*((pA -
                                    disA)^2 - pA^2) + a*disA)/(2t)) +
((
                          p1 - cB)*(c -
              d*p1) + (pA - disA - cA)(a - b*(pA - disA)) - (pA -
            cA)(a - b*pA))*(-(a - b*(pA - disA))/(
              2t))) == 0, (1 - alpha)*((c - d*p1 - d*(p1 -
                  cB))*(0.5 + ((d/2)*(p1^2 - p2^2) - c*(p1 -
                        p2))/(2t)) + (p1 - cB)*(c - d*p1)*(-
                  c + d*p1)/(2t)) + (1 -
                     alpha - bta)*(((pA - disA - cA)*(a -

                  b*(pA - disA)) - (pA - cA)*(a - b*
        pA))*(-c + d*p1)/(2t) + (c - d*p1 - d(
            p1 - cB))*((
                      b/2)((pA - disA)^2 - pA^2) + a*disA)/(2t)) ==
                          0, (1 - alpha)*((c - d*p2 - d(p2 - cB))*(
        0.5 - ((d/
                  2)*(p1^2 - p2^2) - c*(p1 - p2))/(2t)) + (
                        p2 - cB)*(c - d*p2)*(-c + d*p2)/(
                        2t)) - (1 - alpha - bta)*(c - d*p2 - d(p2 -
cB))*((
                              b/2)*((pA - disA)^2 - pA^2) + a*disA)/(
                  2t) == 0}, {pA, p1, p2, disA}];
BR = DeleteCases[B, {pA -> _Complex, p1 -> _Complex,
             p2 -> _Complex, disA -> _Complex}];
SB = Select[BR, And @@ (({pA > 0, p1 > 0, p2 >
               0, disA > 0, pA - disA > 0} /. #)) &]

• Follow-Ups:
  • Re: My problem when solving a system of equations
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>