HP 40gs User Manual page 199

DIVPC
N O T E :
FOURIER
Computer Algebra System (CAS)
DERVX(F)
Or, if you have defined F(X) using DEF, that is, if you have
typed:
-------------- -
DEF(F(X) =
X
then type:
DERVX(F(X))
Simplify the result to get:
2
⋅
3 x – 1
-------------------------------- -
–
4 2
⋅
x – 2 x + 1
Division in increasing order by exponent
DIVPC has three arguments: two polynomials A(X) and
≠
B(X) (where B(0)
DIVPC returns the quotient Q(X) of the division of A(X) by
B(X), in increasing order by exponent, and with deg(Q)
<= n or Q = 0.
Q[X] is then the limited nth-order expansion of:
A X [ ]
----------- -
B X [ ]
in the vicinity of X= 0.
Typing:
2
DIVPC(1+X +X
gives:
3 5
1 + x – x
When the calculator displays a request to change to
increasing powers mode, respond yes.
Fourier coefficients
FOURIER has two parameters: an expression f(x) and a
whole number N.
FOURIER returns the Fourier coefficient c
considered to be a function defined over interval [0, T]
X X + 1
⎛ ⎞ ⎞
------------ -
+ LN
⎝ ⎠ ⎠
X 1 –
2
– 1
0), and a whole number n.
3 2
,1+X ,5)
of f(x),
N
14-17