Description: This function computes at (Xi,Yi) unknown locations the IDW (w<0) or the SMA (w=0) predictions using r1 neighbourhood type ('n':number of points; 'r':radius) and r2 neighbourhood size from Vc measured values at (Xc,Yc) locations.
OUTPUTS Vi: (mandatory) [PxQ] gIDW interpolated values > P=1, Q=1 yields interpolation at one point > P>1, Q=1 yields interpolation at a vector of points > P>1, Q>1 yields interpolation at a (ir)regular grid of points ========================================
INPUTS Xc: (mandatory) [Nx1] x coordinates of known points Yc: (mandatory) [Nx1] y coordinates of known points Vc: (mandatory) [Nx1] known values at [Xc, Yc] locations Xi: (mandatory) [PxQ] x coordinates of points to be interpolated Yi: (mandatory) [PxQ] y coordinates of points to be interpolated w: (mandatory) [scalar] distance weight > w<0, for Inverse Distance Weighted interpolation [IDW] > w=0, for Simple Moving Average (only if neighorhood size is local and not global) [SMA] r1: (optional) [string] neighbourhood type > 'n' (default) number of neighbours > 'r' fixed radius length r2: (optional) [scalar] neighbourhood size > number of neighbours, if r1=='n' default is length(Xc) > radius length, if r1=='r' default is largest distance between known points ========================================
SYNTAX  IDW  all inputs: Vi = gIDW(Xc,Yc,Vc,Xi,Yi,2,'n',30); 6 inputs: Vi = gIDW(Xc,Yc,Vc,Xi,Yi,2); > r1='n'; r2=length(Xc); 7 inputs: Vi = gIDW(Xc,Yc,Vc,Xi,Yi,2,'n'); > r2=length(Xc); Vi = gIDW(Xc,Yc,Vc,Xi,Yi,2,'r'); > r2=largest distance between know points [Xi,Yi] (see D1 calculation)  SMA  Vi = gIDW(Xc,Yc,Vc,Xi,Yi,0,'n',10);  Spatial Map  Vi = gIDW(Xc,Yc,Vc,Xi,Yi,2,'n',10); with Xi and Yi 2D arrays of coordinates relative to an (ir)regular grid. ========================================
EXAMPLES Interpolation at one point location: Vi = gIDW([1:1:10]',[2:2:20]',rand(10,1)*100,5.5,11,2,'n');  Interpolation at a regular grid of unknown points: XYc = [1:1:10]'; Vc = rand(10,1)*100; Xi = rand(50,50)*10; Yi = rand(50,50)*10; [Xi,Yi] = meshgrid(XYc); Vi = gIDW(XYc,XYc,Vc,Xi,Yi,2,'r',3); hold on mapshow(Xi,Yi,Vi,'DisplayType','surface') colormap gray scatter(XYc,XYc,Vc,'filled','MarkerFaceColor','g','MarkerEdgeColor','y') axis([0,11,0,11]) hold off
License: Freeware Related: r13d039n039, gidwxcycvcxiyi, inputs, dlengthxc, Calculation, dlargest, Syntax, Radius, fixed, 039r039, Length, r13d3d039n039, largest, r13d3d039r039, lengthxc O/S:BSD, Linux, Solaris, Mac OS X File Size: 10.0 KB Downloads: 29

