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Topic: Numerical solution from Module
Replies: 1   Last Post: May 12, 2014 12:44 AM

 Messages: [ Previous | Next ]
 Yuk Chai Posts: 7 Registered: 12/11/04
Numerical solution from Module
Posted: May 9, 2014 2:07 AM

Hello every one,

Here is a simple question. Say I define a function

In[14]:= f[x_] := a*x^2 + b*x + c

Then I use Module to frame the solution of f[x] ==0

In[15]:= soln[a_, b_, c_] := Module[{}, xsoln = Solve[f[x] == 0 , x]; x /.
xsoln]

When I enter numerical values for parameters a, b, and c in the module, f[x]
never sees these numerical values, and returns a symbolic solution.

In[11]:= soln[1, -3, 2]

Out[11]= {(-b - Sqrt[b^2 - 4 a c])/(2 a), (-b + Sqrt[b^2 - 4 a c])/(2 a)}

But I want the module to return a numerical solution as:

{{x -> 1}, {x -> 2}}

My question is: without bringing f[x] explicitly into the Module function,
and without redefining f as f[a_,b_,c_][x] := a*x^2+b*x+c, how can I get the
module to return a numerical solution?

Thanks - Rob Chai

Date Subject Author
5/9/14 Yuk Chai
5/12/14 Kevin J. McCann