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+--- Thread: warning in pade (/thread-2198.html)
warning in pade - Alberto Candel - 09-28-2014 04:01 PM
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.
RE: warning in pade - parisse - 09-29-2014 06:33 AM
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.