IMSL ppval function

Question

I am trying to use PPVAL function from the IMSL library, to evaluate a piecewise polynomial, similar to MATLAB's ppval function.

Sadly, I could not understand well the documentation on how to properly use the function. I tried to evaluate a simple polynomial. The polynomials p(x) = 1 and p(x) = x were ok. What I don't understand is when I try to get higher degree polynomials.

The program below tries to evaluate the polynomial p(x)=x^4:

program main
    include 'LINK_FNL_SHARED.h'
    USE PPVAL_INT
    implicit none

    double precision :: x(11), y(11)
    double precision :: BREAK(2),PPCOEF(5,1)
    integer :: ii

    break = [0.0d0,10.0d0] ! breakpoints in increasing order
    PPCOEF(:,1) = [0.0d0,0.0d0,0.0d0,0.0d0,1.0d0] ! polynomial coefficients
    x = dble([0,1,2,3,4,5,6,7,8,9,10])

    do ii=1,11
        y(ii) = PPVAL(x(ii),break,PPCOEF)
    end do

    print *, 'x = ', x
    print *, 'y = ', y
    pause
end program main

But the function returns the polynomial p(x) = x^4/4!. For degrees 2,3 and 5, the return is always, p(x) = x^2/2!, p(x)=x^3/3!, p(x)=x^5/5!. Why does this factor appear in the ppval function? Why can't I just supply the polynomial coefficients and evaluate it?

Is there another simpler function to evaluate polynomials in Fortran, like MATLAB polyval?