ChapterUn

Chebyshev polynomial of the second kind.

Loading LOADSUB ALL FROM "CHEBY.HTS"

or LOADSUB FROM "MATHLIB.HTS"

Usage INTEGER N

REAL X,Y

Y=FNUn(N,X)

Description

FNUn returns the value of the Chebyshev polynomial of the second kind and order n of x, Un(x). N must be positive or zero. Un(x) is defined for all values of x, although it is most commonly used only with values of x between -1 and +1.

Errors

FNUn causes an HTBasic error if its arguments are not of the types listed in the USAGE section, above, or if the polynomial's absolute value would be larger than MAXREAL, the largest value representable.

Un(x)

See Also Tn

Note

For n > 12, the algorithm used computes the value of Un using a recursion from the values of U11 and U12. The computation time increases with n-11 and the computation accuracy decreases with n-11.