FNTnreturns the value of the Chebyshev polynomial of the first kind and ordernofx,Tn(x).Nmust be positive or zero.Tn(x) is defined for all values ofx, although it is most commonly used only with values ofxbetween -1 and +1.
There are other, less used, types of Chebyshev polynomials defined that are not included in the Math Library. These can easily calculated fromTn(x) andUn(x) by using the following formulas:
Tn(x)
Errors
FNTncauses 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.
See Also
Un
Note
Forn> 12, the algorithm used computes the value ofTnusing a recursion from the values ofT11 andT12. The computation time increases withn-11 and the computation accuracy decreases withn-11.