Problems solving using Solve

• To: mathgroup at smc.vnet.net
• Subject: [mg68809] Problems solving using Solve
• From: "akil" <akomur at wanadoo.nl>
• Date: Sat, 19 Aug 2006 00:41:17 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```I have a problem suing the following code:

Cone[beta_, v_,rcAB_,rcCD_,ax_,ay_,cx_,cy_,centerOfMassx_,centerOfMassy_] :=
Module[
{betaUsed, vtemp, fx, fy, ex, ey,
waarde,criticalRC,criticalHeight,xVerplaatsing,ePx2Py2},
betaUsed = beta ;
vtemp = v;
fline[x_] := Tan[betaUsed]x - Tan[betaUsed]vtemp;
fx = x /. Solve[fline[x] == cd[x,rcCD,cx,cy], x][[1]];
fy = cd[fx,rcCD,cx,cy];
criticalRC = (centerOfMassy - fy)/(centerOfMassx - fx);
criticalHeight = -criticalRC*fx + fy;
ex = (-ay + rcAB*ax + criticalHeight)/(rcAB + (-criticalRC));
ey = ab[ex,rcAB,ax,ay];
xVerplaatsing = ex - vtemp;
ePx2Py2 = Sqrt[xVerplaatsing^2 + ey^2];
waarde = xVerplaatsing/ePx2Py2;
ArcCos[-waarde]
];

afg =
Simplify[D[Cone[beta,v,rcAB,rcCD,ax,ay,cx,cy,centerOfMassx,centerOfMassy],v],
TimeConstraint -> 1 ];
Solve[afg== 0, v];

eg.
{ax,ay}= {-44.9376, 36.1678} and {cx,cy}= {17.8329, 122.477} and
{centerOfMassx,centerOfMassy}={-18.6338,72.3356} and rcAB=-0.166667 and
rcCD=-0.37931

Doing the Solve[afg== 0, v] takes ages (after an hour I quit it). Is there
any way I can make it work faster? Is any code in Cone such that it
unnecessarily makes it run faster? So are there any ways I can try to make
everything run faster? Using integers it runs, but it takes too long when
using real cones (made up of four points A B C D and a centerOfMass).

Akil

```

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