Library: | xplore |
See also: | approx |
Quantlet: | linapprox | |
Description: | interpolates linearly from given discretized one-dimensional functions on the same grid. |
Usage: | y = linapprox(f,x {,v}) | |
Input: | ||
f | n x 2 matrix of x-values (first column) and function values (second to last column), sorted by the first column. | |
x | m x 1 vector of new x-values. | |
v | optional scalar, value to be set outside the range of f[,1]. If not given, linear extrapolation is used. | |
Output: | ||
y | m x (p-1), vector of new function values. |
library("xplore") z=(1:5)*2 f=z~(z^2) randomize(117) x=uniform(8)*10 y=linapprox(f,x) y library("plot") f=setmask(f,"medium","green","fillcircle","line","green") plot(setmask(x~y,"large","cross"),f)
A graph with the original and interpolated values is shown. Contents of y [1,] -4.9646 [2,] 37.317 [3,] 13.42 [4,] 1.7342 [5,] 66.715 [6,] 69.481 [7,] 61.838 [8,] 42.354
library("xplore") z=(1:5)*2 f=z~(z^2) randomize(117) x=uniform(8)*10 y1=linapprox(f,x) y2=linapprox(f,x,NaN) y1~y2
Contents of _tmp [1,] -4.9646 +NaN [2,] 37.317 37.317 [3,] 13.42 13.42 [4,] 1.7342 +NaN [5,] 66.715 66.715 [6,] 69.481 69.481 [7,] 61.838 61.838 [8,] 42.354 42.354