On Sat, Feb 27, 2016 at 9:40 AM, Uwe Fechner <[email protected]> wrote:
> Hello, > > I don't think, that this works on a non-uniform grid. The array xg is > evenly spaced, and it > is NOT passed to the function InterpGrid. > > I've recently tried Dierckx which support non-uniform interpolation. I only need very basic functions so I don't know if it has all the flexibility you need but it's probably worth a look if you haven't. > Uwe > > > On Saturday, February 27, 2016 at 3:33:06 PM UTC+1, Cedric St-Jean wrote: >> >> Hi Uwe, >> >> Have you tried Grid.jl? I haven't tried it, but this example looks like >> it might work with a non-uniform grid. >> >> # Let's define a quadratic function in one dimension, and evaluate it on an >> evenly-spaced grid of 5 points: >> c = 2.3 # center >> a = 8.1 # quadratic coefficient >> o = 1.6 # vertical offset >> qfunc = x -> a*(x-c).^2 + o >> xg = Float64[1:5] >> y = qfunc(xg) >> yi = InterpGrid(y, BCnil, InterpQuadratic) >> >> >> >> >> On Saturday, February 27, 2016 at 9:21:53 AM UTC-5, Uwe Fechner wrote: >>> >>> Hello, >>> >>> I am trying to port the following function from python to julia: >>> >>> # -*- coding: utf-8 -*- >>> from scipy.interpolate import InterpolatedUnivariateSpline >>> import numpy as np >>> from pylab import plot >>> >>> P_NOM = [1.5, 2.2, 3.7, 5.6, 7.5, 11.2, 14.9] >>> ETA = [93., 94., 94., 95., 95., 95.5, 95.5] >>> >>> calc_eta = InterpolatedUnivariateSpline(P_NOM, ETA, k=1) >>> >>> # plotting code, only for testing >>> if __name__ == "__main__": >>> X = np.linspace(1.5, 14.9, 1024, endpoint=True) >>> ETA = [] >>> for alpha in X: >>> eta = calc_eta(alpha) >>> ETA.append(eta) >>> plot(X, ETA) >>> >>> The resulting plot is shown at the end of this posting. >>> >>> How can I port this to Julia? >>> >>> I am trying to use the package "Interpolations.jl", but I do not see any >>> example, that shows the interpolation on a non-uniform grid. >>> >>> For now I need only linear interpolation, but I want to use B-Splines >>> later. >>> >>> Any hint appreciated! >>> >>> Uwe Fechner >>> >>> >>> >>> <https://lh3.googleusercontent.com/-8OofwCQWohg/VtGwKR-1BOI/AAAAAAAAAQI/UTLksCCMIPo/s1600/LinearInterpolation.png> >>> >>
