INTERPOLATION
homepage.math.uiowa.edu › ~atkinson › ftpQUADRATIC INTERPOLATION We want to find a polynomial P2(x)=a0 + a1x+ a2x2 which satisfies P2(xi)=yi,i=0,1,2 for given data points (x0,y0),(x1,y1),(x2,y2). One formula for such a polynomial follows: P2(x)=y0L0(x)+y1L1(x)+y2L2(x)(∗∗) with L0(x)= (x−x1)(x−x2) (x0−x1)(x0−x2),L1(x)= (x−x0)(x−x2) (x1−x0)(x1−x2) L2(x)= (x−x0)(x−x1)
INTERPOLATION - University of Iowa
homepage.math.uiowa.edu/~atkinson/ftp/ENA_Materials/Overhead…INTERPOLATION Interpolation is a process of finding a formula (often a polynomial) whose graph will pass through a given set of points (x,y). As an example, consider defining x0 =0,x1 = π 4,x2 = π 2 and yi=cosxi,i=0,1,2 This gives us the three points (0,1), µ π 4, 1 sqrt(2) ¶, ³ π 2,0 ´ Now find a quadratic polynomial p(x)=a0 + a1x ...
Quadratic Spline Example
eng.usf.edu/~kaw/download/today/mws_gen_inp_ppt_interpolation_…Quadratic Spline Interpolation (contd) The first derivatives of two quadratic splines are continuous at the interior points. For example, the derivative of the first spline 1. 1 2 a 1 x +b x + c. is 2a 1 x + b. 1. The derivative of the second spline 2. 2 2 a 2 x +b x + c. is 2a 2 x + b. 2. and the two are equal at x = x. 1. giving 2a 1 x 1 +b 1 ...
METHOD OF QUADRATIC INTERPOLATION
people.math.sc.edu › Quadratic_InterpolationMETHOD OF QUADRATIC INTERPOLATION 7 (3.1) f0(x k+1) = 1 2 f000(˘)f0 k f 0 k 1 (x k x k 1) 2 (f0 k f0 k 1) 2 We now want to take advantage of the Mean Value Theorem. We have: f0 k 0f k 1 x k x k 1 = f00˘ 0 Where ˘ 0 2(x k;x k 1). Also note that since f0(x) = 0, we have: (3.2) f 0 i = f 0(x i) 00f(x) = (x i x)f (˘ i) For some ˘ i 2(x i;x), i= k 1, k, k+ 1. Using (3.2) and the
ME 310 Numerical Methods Interpolation
users.metu.edu.tr › csert › me310(c) Quadratic interpolation. x 0 = 4.5, x 1 = 5.5 , x 2 = 6 f[x 1, x 0] = 0.0871502 (already calculated) f[x 2, x 1] = [f(6) –f(5.5)] / (6 –5.5) = 0.0755772 f[x 2, x 1 , x 0] = {f[x 2, x 1] - f[x 1, x 0]} / (6 –4.5) = -0.0077153 f(5) 0.696788 + (5 - 4.5)(5 - 5.5) (-0.0077153) = 0.698717 e t = 0.04 % •Note that 0.696788 was calculate in part (b).