warning in pade

09282014, 04:01 PM
Post: #1




warning in pade
Hi,
I was working on finding a reasonable expression for a Pade approximation to sin(x). The HP Prime has pade(f(x),x,n,p) which outputs a rational function approximation to f(x) of order less than or equal to n+1 with numerator of degree <p. It works OK, for example pade(sin(x),x,5,4) returns (7*x^3+60*x)/(3*x^2+60) as expected. But for some values of the parameters n, p, the Prime gives a warning before returning the answer. For example pade(sin(x),x,5,3) shows Solution may be wrong since a and b are not prime together. Does anyone know what is happening? What are a and b? Thanks A. 

09292014, 06:33 AM
Post: #2




RE: warning in pade
It means that the extended euclidean algorithm used to solve for Pade approximation returns 2 polynomials that are not prime together, therefore the approxmant will probably loose one or more order.


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