Question

我想创建一个动画来演示基于Sum-Product Algorithm

的LDPC编码

到目前为止，我已经创建了一个图表，显示符号节点（左）和奇偶校验节点（右）alt text http://img29.imageshack.us/img29/9780/ldpc.jpg之间的连接，并希望设置从符号到奇偶校验节点并返回的点的动画。

通过执行以下方法绘制图：

function drawVertices(H)
hold on;
nodesCount = size(H);
parityNodesCount = nodesCount(1);
symbolNodesCount = nodesCount(2);
symbolPoints = zeros(symbolNodesCount, 2);
symbolPoints(:, 1) = 0;
for i = 0 : symbolNodesCount - 1
    ji = symbolNodesCount - i;
    scatter(0, ji)
    symbolPoints(i + 1, 2) = ji;

end;
parityPoints = zeros(parityNodesCount, 2);
parityPoints(:, 1) = 10;
for i = 0 : parityNodesCount - 1
    ji = parityNodesCount - i;
    y0 = symbolNodesCount/2 - parityNodesCount/2;
    scatter(10, y0 + ji)
    parityPoints(i + 1, 2) = y0 + ji;
end;
axis([-1 11 -1 symbolNodesCount + 2]);
axis off

%connect vertices
d = size(H);
for i = 1 : d(1)
    for j = 1 : d(2)
        if(H(i, j) == 1)
            plot([parityPoints(i, 1) symbolPoints(j, 1)], [parityPoints(i, 2) symbolPoints(j, 2)]);
        end;
    end;
end;

所以我想在这里做的是添加另一个方法，它将起点（x和y）和终点作为参数，并从开始到结束并沿着显示的行返回动画一个行进的圆（点）。 / p>

如果有人能够展示解决方案或建议任何有关matlab仿真的有用教程，我将不胜感激。

谢谢！

Answer 1

我相信最好的学习方式就是举例。所以我建议你看一下MATLAB附带的演示lorenz：

edit lorenz

对于其他酷动画，请查看Cleve Moler的书中的orbits.m和swinger.m演示：Experiments with MATLAB

我在这里展示了一个沿着圆形路径移动的点的简单动画。保留的想法归结为使用EraseMode设置为xor，并为每次迭代更新点的XData和YData：

%# coordinates
t = (0:.01:2*pi)';         %# 'fix SO syntax highlight
D = [cos(t) -sin(t)];

%# setup a figure and axis
hFig = figure('Backingstore','off', 'DoubleBuffer','on');
hAx = axes('Parent',hFig, 'XLim',[-1 1], 'YLim',[-1 1], ...
          'Drawmode','fast', 'NextPlot','add');
axis(hAx, 'off','square')

%# draw circular path
line(D(:,1), D(:,2), 'Color',[.3 .3 .3], 'LineWidth',1);

%# initialize point
h = line('XData',D(1,1), 'YData',D(1,2), 'EraseMode','xor',  ...
        'Color','r', 'marker','.', 'MarkerSize',50);
%# init text
hTxt = text(0, 0, num2str(t(1)), 'FontSize',12, 'EraseMode','xor');

i=0;
while true
    i = rem(i+1,numel(t)) + 1;               %# circular increment
    set(h,'XData',D(i,1), 'YData',D(i,2))    %# update X/Y data
    set(hTxt,'String',num2str(t(i)))         %# update angle text
    drawnow                                  %# force refresh
    if ~ishandle(h), return; end             %# in case you close the figure
end

有关所用参数的详细说明（EraseMode，Backingstore，DoubleBuffer，..），请参阅此animation guide

Answer 2

来自documentation for comet.m

t = 0:.01:2*pi;
x = cos(2*t).*(cos(t).^2);
y = sin(2*t).*(sin(t).^2);
comet(x,y);

Matlab仿真：点（符号）从起点到终点和后退

2 个答案: