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 Author Comment/Response Charles 12/12/07 6:19pm Hi, I have a mathematica question. It is bugging me allot. I am just doing some simple algebra in Mathematica: In[1]:= q[r_] := qo*(1 - r/a) In[2]:= wH[r_] := c1*r^2*Log[r] + c2*Log[r] + c3*r^2 + c4; In[3]:= wP[r_] := (q[r]*r^4)/(64*K); In[4]:= w[r_] := wP[r] + wH[r] In[5]:= w[r] Out[5]= c4 + c3 r^2 + (qo r^4 (1 - r/a))/(64 K) + c2 Log[r] + c1 r^2 Log[r] In[6]:= c1 = 0; In[7]:= c2 = 0; In[8]:= w[r] Out[8]= c4 + c3 r^2 + (qo r^4 (1 - r/a))/(64 K) In[9]:= A[r_] := D[w[r], {r, 1}] In[10]:= A[r] (This is correct, it too the differential of w[r] correct!) Out[10]= 2 c3 r - (qo r^4)/(64 a K) + (qo r^3 (1 - r/a))/(16 K) But when I plug in for r=a, it doesn't give me the right answer! In[15]:= A[a] Out[15]= 2 a c3 A[r=a] should not equal 2*a*c3? What is Mathematica doing A[r=a] should equal = 2*a*c3-(qo*a^3)/(64*K)!!!! Please help. I'm in desperate need. A big Hug for all those help me! Thanks. URL: ,

 Subject (listing for 'Mathematica Substitution') Author Date Posted Mathematica Substitution Charles 12/12/07 6:19pm Re: Mathematica Substitution yehuda ben-s... 12/16/07 07:23am
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