% NEVILLE'S ITERATED INTERPOLATION ALGORITHM 3.1
%
% To evaluate the interpolating polynomial P on the
% (n+1) distinct numbers x(0), ..., x(n) at the number x
% for the function f:
%
% INPUT: numbers x(0),..., x(n) as XX(0),...,XX(N);
% number x; values of f as the first column of Q
% or may be computed if function f is supplied.
%
% OUTPUT: the table Q with P(x) = Q(N+1,N+1).
syms('TRUE', 'FALSE', 'OK', 'FLAG', 'N', 'I', 'XX', 'Q', 'A', 'NAME');
syms('INP', 'X', 'D', 'J', 'OUP','x','s');
TRUE = 1;
FALSE = 0;
fprintf(1,'This is Nevilles Method.\n');
OK = FALSE;
while OK == FALSE
fprintf(1,'Choice of input method:\n');
fprintf(1,'1. Input entry by entry from keyboard\n');
fprintf(1,'2. Input data from a text file\n');
fprintf(1,'3. Generate data using a function F\n');
fprintf(1,'Choose 1, 2, or 3 please\n');
FLAG = input(' ');
if FLAG == 1 | FLAG == 2 | FLAG == 3
OK = TRUE;
end
end
if FLAG == 1
OK = FALSE;
while OK ~= TRUE
fprintf(1,'Input n\n');
N = input(' ');
if N > 0
OK = TRUE;
XX = zeros(1,N+1);
Q = zeros(1,N+1;1,N+1);
for I = 0:N
fprintf(1,'Input X(%d) and F(X(%d)) ', I, I);
fprintf(1,'separated by a space\n');
XX(I+1) = input(' ');
Q(I+1,1) = input(' ');
end
else
fprintf(1,'Number must be a positive integer\n');
end
end
end
if FLAG == 2
fprintf(1,'Has a text file been created with the data in two
columns?\n');
fprintf(1,'Enter Y or N\n');
A = input(' ','s');
if A == 'Y' | A == 'y'
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