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Why does poly() not evalp

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Billy
Billy 2011-6-14
I have an example:
evalp( poly( sqrt( 1-x^2 ), [x] ), x=cos(0.5) )
This gives (sqrt(1-x^2)) as the response.
The expected result is only given by
evalp( poly( sqrt( 1-x^2 ), [x] ), x=cos(0.5) ) | x=cos(0.5)
And evalp works as expected with simple expression like
evalp( poly( x, [x] ), x = 1 )
Is this a bug?

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Walter Roberson
Walter Roberson 2011-6-15
sqrt( 1-x^2 ) is not a polynomial. evalp() is only for evaluating polynomials.
I am not familiar with the way you used "|" in your second expression. I looked through the Standard Library but I do not find any meaning defined for "|" . Could you give a reference on that?
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Billy
Billy 2011-6-15
I'm using poly() to simulate the output of my P function I just wrote, which outputs a poly() (in turn because orthpoly::legendre outputs a poly).
Ultimately I'm trying to evaluate the legendre polynomials with cos(t) in the place of x in legendre(n,x).
Billy
Billy 2011-6-15
The P function is here: http://www.mathworks.com/matlabcentral/answers/9485-how-do-i-specify-m-for-orthpoly-legendre

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