for j=1:p0*N for i=1;a init_sample=x(i,:) n_samples= (1-p0)/p0; prop_dist = proposal(mu, sigma); [samples, acceptance_rate] = mcmc(@target, prop_dist, init_sample, n_samples); %生成MCMC链 for i=1:n_samples values = cell(1, N); for i = 1:N values{i} = @(i) target(samples(i,:)); end failures(i) = sum(values(i) <= 0); end end value = sort(values) ; F=value(end); end for l=1:m A=cell(1,N); A(m)=F; end end，，'cell' 类型的操作数不支持运算符 '<='。，如何改正

在代码中，你将一个函数句柄数组存储在单元格数组中，然后想要计算这些函数的值是否小于等于0。但是，单元格数组不支持“<=”运算符，因此需要对代码进行修改。

一种可能的解决方案是使用循环，遍历单元格数组中的每个函数句柄，并检查其值是否小于等于0。以下是修改后的代码示例：

for i = 1:N
    for j = 1:n_samples
        if values{j}(i) <= 0
            failures(j) = failures(j) + 1;
        end
    end
end

在此修改后的代码中，我们首先使用两个嵌套循环遍历所有样本及其对应的函数句柄。然后，我们使用函数句柄来计算函数值，并将其与0进行比较。如果函数值小于等于0，则将相应样本的失败计数器增加1。

请注意，我们还将“failures(i)”更改为“failures(j)”，因为我们现在正在使用嵌套循环遍历样本和函数句柄，而不是在单个循环中遍历样本。

希望这可以帮助你解决问题！

相关问题

function y = target3(x) if numel(size(x)) ~= 2 || size(x, 2) ~= 3 error('x must be an Nx3 matrix'); end if size(x, 1) == 1 && size(x, 2) > 1 x = x.'; end y = x(:,1).^3 + 2.*x(:,2) - 5.*x(:,3); end %% function [samples, acceptance_rate] = mcmc(target3, prop_dist, init_sample, n_samples) samples = zeros(n_samples, 3); samples(1, :) = init_sample; acceptance_rate = 0; for i = 2:n_samples prop_sample = prop_dist.sample(); target_ratio = target3(prop_sample)/target3(samples(i-1, :)); prop_ratio = mvnpdf(samples(i-1, :), prop_sample, prop_dist.sigma)/mvnpdf(prop_sample, samples(i-1, :), prop_dist.sigma); alpha = min(1, target_ratio*prop_ratio); if rand() < alpha samples(i, :) = prop_sample; acceptance_rate = acceptance_rate + 1; else samples(i, :) = samples(i-1, :); end prop_dist.update(samples(1:i, :)); end acceptance_rate = acceptance_rate/n_samples; end %% 出错 target3 (第 8 行) y = x(:,1).^3 + 2.*x(:,2) - 5.*x(:,3); 出错 mcmc (第 7 行) target_ratio = target3(prop_sample)/target3(samples(i-1, :)); %% 如何改正

在target3函数中，应该保证x的大小为Nx3。因此，可以将第8行改为：

y = x(:,1).^3 + 2.*x(:,2) - 5.*x(:,3);

在mcmc函数中，计算target_ratio时会调用target3函数，因此需要保证prop_sample和samples(i-1,:)都是Nx3的矩阵。可以在调用target3函数前添加以下代码：

if size(prop_sample, 2) ~= 3 || size(samples(i-1,:), 2) ~= 3
    error('prop_sample and samples must be Nx3 matrices');
end

这样可以确保prop_sample和samples(i-1,:)都是Nx3的矩阵。完整的函数代码如下：

function y = target3(x)
if numel(size(x)) ~= 2 || size(x, 2) ~= 3
    error('x must be an Nx3 matrix');
end
if size(x, 1) == 1 && size(x, 2) > 1
    x = x.';
end
y = x(:,1).^3 + 2.*x(:,2) - 5.*x(:,3);
end

function [samples, acceptance_rate] = mcmc(target3, prop_dist, init_sample, n_samples)
samples = zeros(n_samples, 3);
samples(1, :) = init_sample;
acceptance_rate = 0;
for i = 2:n_samples
    prop_sample = prop_dist.sample();
    if size(prop_sample, 2) ~= 3 || size(samples(i-1,:), 2) ~= 3
        error('prop_sample and samples must be Nx3 matrices');
    end
    target_ratio = target3(prop_sample)/target3(samples(i-1, :));
    prop_ratio = mvnpdf(samples(i-1, :), prop_sample, prop_dist.sigma)/mvnpdf(prop_sample, samples(i-1, :), prop_dist.sigma);
    alpha = min(1, target_ratio*prop_ratio);
    if rand() < alpha
        samples(i, :) = prop_sample;
        acceptance_rate = acceptance_rate + 1;
    else
        samples(i, :) = samples(i-1, :);
    end
    prop_dist.update(samples(1:i, :));
end
acceptance_rate = acceptance_rate/n_samples;
end

function y = target3(x) if numel(size(x)) ~= 2 || size(x, 2) ~= 3 error('x must be an Nx3 matrix'); end if size(x, 1) == 1 && size(x, 2) > 1 x = x.'; end y = x(:,1).^3 + 2.*x(:,2) - 5.*x(:,3); end function [samples, acceptance_rate] = mcmc(target3, prop_dist, init_sample, n_samples) samples = zeros(n_samples, 3); samples(1, :) = init_sample; acceptance_rate = 0; for i = 2:n_samples prop_sample = prop_dist.sample(); if size(prop_sample, 2) ~= 3 || size(samples(i-1,:), 2) ~= 3 error('prop_sample and samples must be Nx3 matrices'); end target_ratio = target3(prop_sample)/target3(samples(i-1, :)); prop_ratio = mvnpdf(samples(i-1, :), prop_sample, prop_dist.sigma)/mvnpdf(prop_sample, samples(i-1, :), prop_dist.sigma); alpha = min(1, target_ratio*prop_ratio); if rand() < alpha samples(i, :) = prop_sample; acceptance_rate = acceptance_rate + 1; else samples(i, :) = samples(i-1, :); end prop_dist.update(samples(1:i, :)); end acceptance_rate = acceptance_rate/n_samples; end %% 出错 target3 (第 8 行) y = x(:,1).^3 + 2.*x(:,2) - 5.*x(:,3); 出错 mcmc (第 12 行) target_ratio = target3(prop_sample)/target3(samples(i-1, :)); %% 如何改正

在计算 `target_ratio` 时，需要将 `target3` 函数的输出值转化为标量，而不是一个向量。可以使用 `sum` 函数将向量的元素加和，得到一个标量。修改后的代码如下：

function y = target3(x)
if numel(size(x)) ~= 2 || size(x, 2) ~= 3
    error('x must be an Nx3 matrix');
end
if size(x, 1) == 1 && size(x, 2) > 1
    x = x.';
end
y = sum(x(:,1).^3 + 2.*x(:,2) - 5.*x(:,3)); % 修改此行
end

function [samples, acceptance_rate] = mcmc(target3, prop_dist, init_sample, n_samples)
samples = zeros(n_samples, 3);
samples(1, :) = init_sample;
acceptance_rate = 0;
for i = 2:n_samples
    prop_sample = prop_dist.sample();
    if size(prop_sample, 2) ~= 3 || size(samples(i-1,:), 2) ~= 3
        error('prop_sample and samples must be Nx3 matrices');
    end
    target_ratio = target3(prop_sample)/target3(samples(i-1, :));
    prop_ratio = mvnpdf(samples(i-1, :), prop_sample, prop_dist.sigma)/mvnpdf(prop_sample, samples(i-1, :), prop_dist.sigma);
    alpha = min(1, target_ratio*prop_ratio);
    if rand() < alpha
        samples(i, :) = prop_sample;
        acceptance_rate = acceptance_rate + 1;
    else
        samples(i, :) = samples(i-1, :);
    end
    prop_dist.update(samples(1:i, :));
end
acceptance_rate = acceptance_rate/n_samples;
end