HP 49g+, User Manual, Page: 627 / 862

Page 18-60
Here is the
translation of the algorithm to a program in User RPL language.
(See Chapter 21 for additional information on programming):
«
Open program
x y p Enter lists x and y, and p (levels 3,2,1)
«
Open subprogram 1
x SIZE n Determine size of x list
«
Open subprogram 2
x VANDERMONDE Place x in stack, obtain
V
n
IF ‘p<n-1’ THEN This IF implements step 3 in algorithm
n Place n in stack
p 2 + Calculate p+1
FOR j Start loop j = n-1, n-2, …, p+1, step = -1
j COL
−
DROP Remove column and drop it from stack
-1 STEP Close FOR-STEP loop
ELSE
IF ‘p>n-1’ THEN
n 1 +
Calculate n+1
p 1 + Calculate p+1
FOR j Start a loop with j = n, n+1, …, p+1.
x j ^ Calculate
x j
, as a list
OBJ ARRY Convert list to array
j COL+ Add column to matrix
NEXT Close FOR-NEXT loop
END Ends second IF clause.
END Ends first IF clause. Its result is
X
y OBJ ARRY Convert list
y
to an array
MTREG
X
and
y
used by program MTREG
NUM Convert to decimal format
»
Close sub-program 2
»
Close sub-program 1
»
Close main program
Save it into a variable called POLY (POLYnomial fitting).