Inverse Distance Weighted (IDW) or Simple Moving Average (SMA) INTERPOLATION 1.0

This function computes at (Xi,Yi) unknown locations the IDW (w 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 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

Requirements:	No special requirements
Platforms:	Matlab
Keyword:	039r039,  Calculation,  Dlargest,  Dlengthxc,  Fixed,  Gidwxcycvcxiyi,  Inputs,  Largest,  Length,  Lengthxc,  R13d039n039,  R13d3d039n039,  R13d3d039r039,  Radius,  Syntax
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