Compiled Function Problem

• To: mathgroup at smc.vnet.net
• Subject: [mg18265] Compiled Function Problem
• From: Zahnd Beat <zahnb at hta-bi.bfh.ch>
• Date: Thu, 24 Jun 1999 14:24:50 -0400
• Organization: Engineering School Biel
• Sender: owner-wri-mathgroup at wolfram.com

```Hello NG

This function calculates the area of two 4 sides Polygons. It works woll
in its uncompiled form, but not in compiled form.

It seems that the function Cross ditn't work in compiled functions, so I
rewrote it.

In[10]:=
ElementVF = Compile[{{elm1, _Real, 2}, {elm2, _Real, 2}},
Module[{VecAbs, CrossP, area1, area2},

VecAbs[v_] := Sqrt[Plus @@ (v^2)];
CrossP[v1_, v2_] :=
{v1[[2]]*v2[[3]] - v1[[3]]*v2[[2]], v1[[3]]*v2[[1]] -
v1[[1]]*v2[[3]], v1[[1]]*v2[[2]] - v1[[2]]*v2[[1]]};

area1 = (VecAbs[CrossP[elm1[[2]] - elm1[[1]], elm1[[3]] -
elm1[[1]]]] +
VecAbs[CrossP[elm1[[2]] - elm1[[4]], elm1[[3]] -
elm1[[4]]]])/2;

area2 = (VecAbs[CrossP[elm2[[2]] - elm2[[1]], elm2[[3]] -
elm2[[1]]]] +
VecAbs[CrossP[elm2[[2]] - elm2[[4]], elm2[[3]] -
elm2[[4]]]])/2; {area1, area2}]];

In[11]:=
ElementVF[Kreisring[200, 100, 0][[1]], Mantel[200, 0, 40][[1]]]
CompiledFunction::"cfex":
"External evaluation error at instruction 18 proceeding with \
uncompiled evaluation."
Out[12]=
{67.5118,65.4236}

--
Beat Zahnd
Engineering School Biel, Switzerland
http://www.isbiel.ch/~zahnb/

```

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