| xinterp {rjacobi} | R Documentation |
Returns and modifies a interpolation points of a quadrature
x <- xinterp(q) xinterp(q) <- value
q |
An object of class quadrature returned by the quadrature function |
value |
Points where the interpolation should be calculated |
This function is used to set or modify the points where interpolation
occurs. It modifies the fields xinterp and imat of the
an object with class quadrature.
Interpolation points
Abramowitz, Milton and Stegun, Irene (editors); "Handbook of Mathematical functions", Dover Publications 1965.
Karniadakis, George Em and Sherwin, Spencer; "Spectral/hp Element Methods for Computational Fluid Dynamics", Oxford Science Publications, 2nd edition, 2005.
lagrangeGJ
quadrature
quadInterp
interpmatGJ
## Interpolates the Runge function in the interval (-1,1)
runge <- function(x){1 / (1 + 25*x^2)}
q <- quadrature(13, type='GLJ')
z <- q$x
x <- seq(-1, 1, by=0.02)
xinterp(q) <- x
x2 <- seq(-1, 1, len=201)
fe <- runge(x2)
f <- runge(z)
finterp <- quadInterp(q, runge)
plot(x2, fe, ty='l', xlab='x', ylab='y',
main='Runge function interpolation')
points(z, f)
lines(x, finterp, lty=2)