problem with numerical values in Solve/NSolve
- To: mathgroup at smc.vnet.net
- Subject: [mg63726] problem with numerical values in Solve/NSolve
- From: Jacob Grose <jeg35 at Cornell.edu>
- Date: Thu, 12 Jan 2006 03:22:34 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Hello, I writing a physics simulation and I need to solve a system of 41 equations. However, I am having problems even with a more simple 5x5 matrix. The problem is as follows: If I symbolically solve the matrix m1: \!\(\* TagBox[ RowBox[{"(", "\[NoBreak]", GridBox[{ {\(\(-a\) - b - c\), "0", "f", "h", "l"}, {"0", \(\(-c\) - d - e\), "g", "k", "m"}, {"a", "c", \(\(-f\) - g\), "0", "0"}, {"b", "d", "0", \(\(-h\) - k\), "0"}, {"c", "e", "0", "0", \(\(-l\) - m\)} }], "\[NoBreak]", ")"}], Function[ BoxForm`e$, MatrixForm[ BoxForm`e$]]]\) Using the code: variables = Array[p, 5]; evec = Simplify[Solve[m1.variables \[Equal] Table[0, {i, 1, 5}], Array[p, 4]]] I get a result. However, if I try to solve for a matrix (m) of the same form but with values substituted for the variables: \!\(\* TagBox[ RowBox[{"(", "\[NoBreak]", GridBox[{ {\(-1.870413280501348`*^10\), "0", "1.7479373054791087`*^8", " 7.607967609656633`*^9", "2.5605854781972427`*^7"}, {"0 ", \(-1.2870235495030115`*^10\), "206293.3885126606`", \ "8.754725514677356`*^7", "1.3554510956434595`*^10"}, {"1.747937063721231`*^10", "2.062933885126606`*^7 ", \(-1.7500002393642354`*^8\), "0", "0"}, {"1.2247621677975328`*^9", "8.754722967399057`*^9", "0", \ \(-7.695514864803407`*^9\), "0"}, {"0.0036402209477187386`", "4.094883188779791`*^9", "0", "0", \ \(-1.3580116811216568`*^10\)} }], "\[NoBreak]", ")"}], Function[ BoxForm`e$, MatrixForm[ BoxForm`e$]]]\) Using the same code: variables = Array[p, 5]; evec = Simplify[Solve[m.variables \[Equal] Table[0, {i, 1, 5}], Array[p, 4]]] mathematica returns: {}. I tried using Nsolve instead of solve, as well as setting $MaxExtraPrecision = 5000, but it didn't help. Any ideas? Thanks, Jacob