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Calculating polynomials in OF source

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Old   May 28, 2014, 13:44
Default Calculating polynomials in OF source
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Robertas N.
Join Date: Mar 2009
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I noticed that the class member Foam:: polynomial::value() seems to calculate a polynomial by actually calculating the powers:

Code:
  167     forAll(coeffs_, i)
  168     {
  169         y += coeffs_[i].first()*pow(x, coeffs_[i].second());
  170     }
while Foam:: polynomialFunction::value () uses the Horner scheme:

Code:
  168     // avoid costly pow() in calculation
  169     scalar powX = x;
  170     for (label i=1; i<coeffs.size(); ++i)
  171     {
  172         val += coeffs[i]*powX;
  173         powX *= x;
  174     }
I'm just curious -- is there any reason to use the 'pow ()' function (rather than multiplication) in the former?
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