Student Support Forum: 'Thread and Solve problem' topicStudent Support Forum > General > "Thread and Solve problem"

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 Author Comment/Response Forum Moderator email me 10/01/02 10:01am Solve is evaluated before Thread in your example. Your list is treated as a system and the system likely has no solution, hence the empty set. In[36]:= f1 = 3x+2y-z == 4 In[37]:= f2 = x + 2*y - z == 4 In[38]:= f3 = 3*x + y - z == 4 In[39]:= Thread[Solve[{f1,f2,f3},z]] Out[39]= {} Here are some ways to apply Solve to a list of equations. Here is a list: In[50]:= eqns={f1,f2,f3} Out[50]= {3 x + 2 y - z == 4, x + 2 y - z == 4, 3 x + y - z == 4} You can use Table: In[51]:= Table[Solve[eqns[[i]],z],{i, 1, Length[eqns]}] Out[51]= {{{z -> -4 + 3 x + 2 y}}, {{z -> -4 + x + 2 y}}, {{z -> -4 + 3 x + y}}} You could define a new function that uses Solve: In[52]:= solveList[funcs_]:= Solve[funcs,z] and then Map that function onto the list: In[53]:= Map[solveList,eqns] Out[53]= {{{z -> -4 + 3 x + 2 y}}, {{z -> -4 + x + 2 y}}, {{z -> -4 + 3 x + y}}} You can also use a "pure function" in Map to skip the function definition step. In[54]:= Map[Solve[#,z]&, eqns] Out[54]= {{{z -> -4 + 3 x + 2 y}}, {{z -> -4 + x + 2 y}}, {{z -> -4 + 3 x + y}}} URL: ,

 Subject (listing for 'Thread and Solve problem') Author Date Posted Thread and Solve problem Tim Cooper 09/26/02 1:45pm Re: Thread and Solve problem Forum Modera... 10/01/02 10:01am
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