 3 Point Neville's Method - Printable Version +- HP Forums (https://www.hpmuseum.org/forum) +-- Forum: HP Calculators (and very old HP Computers) (/forum-3.html) +--- Forum: HP Prime (/forum-5.html) +--- Thread: 3 Point Neville's Method (/thread-5306.html) 3 Point Neville's Method - Eddie W. Shore - 12-10-2015 08:57 PM HP Prime Program: NEVILLE3 Input: lx and ly and list of three elements, {x0, x1, x2} and {y0, y1, y2}, respectively, and x is the target point. Code: ```EXPORT NEVILLE3(lx,ly,x) BEGIN // Neville 3-Point Approx. // EWS 2015-12-07 LOCAL la,a,y,k,n; la:={0}; // for consistency  FOR k FROM 1 TO 3 DO IF k==3 THEN a:=((lx(3)-x)*la(2)+(x-lx(1))* la(3))/(lx(3)-lx(1)); ELSE a:=((lx(k+1)-x)*ly(k)+(x-lx(k))* ly(k+1))/(lx(k+1)-lx(k)); END; la:=CONCAT(la,{a}); END; y:=la(4); RETURN y; END;``` Example 1; lx = {16, 64, 100} ly = {0.25, 0.125, 0.1} x = 81 Result: 0.1058511078 Example 2: lx = {-2, 0, 2} ly = {11, 4, 11} x = 3 Details and sources: http://edspi31415.blogspot.com/2015/12/hp-prime-and-casio-prizm-3-point.html