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Adding MATLAB post source code
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‎MATLAB_arrayfun/ArrayfunArticle.m‎

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‎MATLAB_arrayfun/README.md‎

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Companion Code for "High-Performance MATLAB with GPU Acceleration" by Joss Knight
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============================
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This folder contains source code from the NVIDIA Parallel Forall Blog post on MATLAB by Joss Stone (The Mathworks) entitled [High-Performance MATLAB with GPU Acceleration](http://developer.nvidia.com/parallel-forall/high-performance-matlab-gpu-acceleration).
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License
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-------
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These examples are released under the BSD open source license. Refer to license.txt in this directory for full details.

‎MATLAB_arrayfun/drawAntenna.m‎

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function drawAntenna(p, h, dir, b, nsections)
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% Draws a 3D representation of an antenna
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% Draw box on the ground
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base = [p+[b;0;0], p+[0;b;0], p+[-b;0;0], p+[0;-b;0], p+[b;0;0]];
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drawline(base);
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% Draw edges of pyramid
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top = p+[0;0;h];
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pyramid = [top, base(:,1), top, base(:,2), top, base(:,3), top, base(:,4)];
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drawline(pyramid);
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% Draw cross on base
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crx = [p+[b;0;0], p+[-b;0;0], p+[0;b;0], p+[0;-b;0]];
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drawline(crx);
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% Draw segments
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if nargin < 5
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nsections = floor(h/b);
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end
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bottom = base;
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sh = h/nsections;
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for s = 1:nsections-1
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up = p + s*[0;0;sh];
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r = ((h-(s*sh))/h) * b;
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top = [up+[r;0;0], up+[0;r;0], up+[-r;0;0], up+[0;-r;0], up+[r;0;0]];
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% Draw top of segment
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drawline(top);
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% Draw crosses on each face
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for f = 1:4
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crx = [bottom(:,1), top(:,2), top(:,1), bottom(:,2)];
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drawline(crx);
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top = circshift(top,1,2);
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bottom = circshift(bottom,1,2);
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end
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bottom = top;
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end
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% Draw antenna direction
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l = norm(dir);
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% Direction perp to dir horizontally
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perph = cross(dir, [0;0;1])/2;
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% Direction perp to dir vertically
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perpv = cross(dir, perph)/l/2;
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% Draw 'Image' plane
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top = p+[0;0;h];
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c = top + dir;
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im = [c+perph+perpv, c+perph-perpv, c-perph-perpv, c-perph+perpv];
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drawline(im);
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% Draw view pyramid
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pyramid = [top, im(:,1), top, im(:,2), top, im(:,3), top, im(:,4)];
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drawline(pyramid);
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end
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function drawline(coords)
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line(coords(1,:), coords(2,:), coords(3,:));
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end

‎MATLAB_arrayfun/drawMap.m‎

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function drawMap(map, masts, dirn, H)
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% Draws a 3D map of the topological data and antenna positions
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close all
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N = size(map,1);
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N2 = sqrt(N);
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M = size(masts,1);
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mapX = reshape(map(:,1), [N2 N2]);
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mapY = reshape(map(:,2), [N2 N2]);
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mapZ = reshape(map(:,3), [N2 N2]);
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mesh(gather(mapX), gather(mapY), gather(mapZ));
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view(-41,41);
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hold on;
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for a = 1:M
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mastBase = masts(a,:)' - [0;0;H];
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scale = 20;
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baseline = 10;
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drawAntenna(mastBase, H*scale, dirn(:,a)*scale*baseline, scale*baseline, 5);
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end
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axis off
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set(gca, 'Position', [0 0 1 1], 'ActivePositionProperty', 'position');
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end

‎MATLAB_arrayfun/drawMultipleSignalMaps.m‎

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function drawMultipleSignalMaps(map, masts, AntennaDirection, H, signalMap)
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% Draws signal maps stored pagewise along dimension 3 of the input
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% signalMap
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close;
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numMaps = size(signalMap,2);
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for m = 1:numMaps
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subplot(1, numMaps, m);
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drawSignalMap(map, masts, AntennaDirection, H, signalMap(:,m));
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opos = get(gca, 'OuterPosition');
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opos(1) = (m-1)/numMaps; % Left
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opos(3) = 1/numMaps; % Width
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set(gca, 'OuterPosition', opos);
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end
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set(gcf, 'MenuBar', 'none');
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oldpos = get(gcf, 'OuterPosition');
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newpos = [oldpos(1:2) [oldpos(3)*1.5 oldpos(4)*0.65]*0.8];
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set(gcf, 'OuterPosition', newpos);
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set(gcf, 'Position', newpos);
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end

‎MATLAB_arrayfun/drawSignalMap.m‎

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function drawSignalMap(map, masts, dirn, H, signalMap)
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% Draws a 2D map of received power at each gridpoint as well as a
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% representation of the antennae.
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hold off
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N = size(map,1);
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N2 = sqrt(N);
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M = size(masts,1);
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mapX = reshape(map(:,1), [N2 N2]);
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mapY = reshape(map(:,2), [N2 N2]);
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mapZ = reshape(map(:,3), [N2 N2]);
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contour(mapX, mapY, mapZ); hold on;
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for a = 1:M
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mastBase = masts(a,:)' - [0;0;H];
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scale = 20;
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baseline = 10;
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drawAntenna(mastBase, H*scale, dirn(:,a)*scale*baseline, scale*baseline, 5);
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end
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colormap hot;
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caxis(gather([min(signalMap) max(signalMap)]));
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surf(mapX, mapY, reshape(signalMap, size(mapX)));
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shading flat;
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grid off;
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axis off;
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end

‎MATLAB_arrayfun/multipleSignalMaps.m‎

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% Given the setup at the start of the article, this script divides the
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% antennae between 3 networks and computes a signal map for each one
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% independently. While this could be done using a loop, we prefer to use
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% vectorized operations to process all the data together.
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% Assign network 1-3 (at random) to each antenna at every point
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Network = gpuArray.randi(3, 1, M);
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NetworkReplicated = repmat(Network, [N 1]);
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% Sort power data and networks by power
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[signalPowerSorted, I] = sort(signalPowerDecibels, 2, 'descend');
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NetworkSorted = NetworkReplicated(sub2ind([N M], RowIndex(:), I(:)));
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% Sort again to group by network
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[~, J] = sort(reshape(NetworkSorted, [N M]), 2);
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signalPowerGrouped = signalPowerSorted(J);
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% Sorting original list and diff finds group boundaries as an index array
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NetworkGrouped = sort(Network);
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groupStartColumn = find(diff([0, NetworkGrouped]));
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% Accumulated sum will allow us to find means without loops
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signalPowerCum = cumsum([zeros(N,1), signalPowerGrouped], 2);
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% Pick out the sum of the three most powerful antennae to get the mean
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signalMap = (signalPowerCum(:,groupStartColumn+3) - ...
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signalPowerCum(:,groupStartColumn)) / 3;
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drawMultipleSignalMaps(map, masts, AntennaDirection, H, signalMap)

‎MATLAB_arrayfun/powerCalculationWithGpuArray.m‎

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function signalPower = powerCalculationWithGpuArray(X, mastPos, Power, Frequency, dirn)
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pathToAntenna = bsxfun(@minus, mastPos, X);
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distanceSquared = sum(pathToAntenna.^2, 3);
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distance = sqrt(distanceSquared);
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pathLoss = (4 .* pi .* distance * Frequency ./ 3e8).^2;
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signalPowerWatts = bsxfun(@rdivide, Power, pathLoss);
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signalPower = 30 + 10 * log10(signalPowerWatts);
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directionDotProduct = sum(bsxfun(@times, pathToAntenna, dirn), 3);
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isFacing = directionDotProduct >= 0;
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signalPower(~isFacing) = -inf;
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end

‎MATLAB_arrayfun/powerKernel.m‎

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function signalPower = powerKernel(X, Y, Z, mastX, mastY, mastZ, Power, Frequency, dirnX, dirnY, dirnZ)
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% Arrayfun kernel for computing received power at [X;Y;Z] from antenna at
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% [mastX; mastY; mastZ]
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pathX = mastX - X; pathY = mastY - Y; pathZ = mastZ - Z;
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distanceSquared = pathX.*pathX + pathY.*pathY + pathZ.*pathZ;
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distance = sqrt(distanceSquared);
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pathLoss = (4 .* pi .* distance .* Frequency ./ 3e8).^2;
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signalPowerWatts = Power ./ pathLoss;
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signalPower = 30 + 10 * log10(signalPowerWatts);
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directionDotProduct = pathX*dirnX + pathY*dirnY + pathZ*dirnZ;
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if directionDotProduct < 0
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signalPower = -inf;
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end
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end

‎MATLAB_arrayfun/reportTime.m‎

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function tnow = reportTime(t, messageString, scale, tbefore)
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if nargin < 3
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scale = 1;
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end
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wait(gpuDevice);
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tnow = t * scale;
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disp([messageString ' = ' num2str(tnow*1e3) 'ms']);
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if nargin > 3
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disp(['Speedup of ' num2str(tbefore/tnow) 'x']);
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end
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end

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