```Date: Apr 5, 2014 1:49 AM
Author: Hagwood, Charles R.
Subject: question

I am so sick of Mathematica.  It no longer seems to be a  package to do applied work, but more for the university types.  I have spent several hours using several combinationsof ?NumberQ  in the following code, but still I get an error.  Last weekend I spend several hours using FunctionExpand to get results I can read.Any help appreciated.r1=1;r2=2;beta2[t_]:={r1*Cos[2*Pi*t],r2*Sin[2*Pi*t]}beta1[t_]:=beta2[t+4.8*t^2*(t-1)^2]q2[t_]:=FunctionExpand[beta2'[t]/Sqrt[Norm[beta2'[t]]],Assumptions->t\[Element] Reals && beta2'\[Element]Vectors[2,Reals]]q1[s_]:=FunctionExpand[beta1'[s]/Sqrt[Norm[beta1'[s]]],Assumptions->s\[Element] Reals&& beta2'\[Element]Vectors[2,Reals]]a[t_, z_] := 2*q1[t].q2'[z] // FunctionExpandb[t_, z_] := q1[t].q2[z] // FunctionExpandc[t_, z_] := 2*q1'[t].q2[z] // FunctionExpandF1[t_, z_] := c[t, z]/b[t, z]F2[t_, z_] := a[t, z]/b[t, z]factor1[s_, z_] := Exp[-NIntegrate[F2[s, u], {u, 0, z}]]factor2[s_, z_] := Exp[NIntegrate[F2[s, u], {u, 0, z}]]g[s_, z_?NumberQ] :=  NIntegrate[factor2[s, tau]*F1[s, tau], {tau, 0, z}]y[s_, z_] := factor1[s, z]*g[s, z]y[.2, .3]I get the errorNIntegrate::nlim: _u_ = _tau_ is not a valid limit of integration
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