调用期间未分配输出参数：Matlab

Posted 2023-02-16

【中文标题】调用期间未分配输出参数：Matlab

【英文标题】：Output Argument Not Assigned During Call: Matlab

【发布时间】：2020-09-28 01:48:15

【问题描述】：

我正在尝试使用 LCG 为一个项目生成 2500 个伪随机数。但是，当我尝试运行代码时，我不断收到错误“在调用 lcgg 期间未分配输出参数‘p’（可能还有其他参数）。”。我希望有人能帮助我理解为什么 p 不在输出中以及如何解决这个问题？

clear;
clc;

M = 2500;
ID = 801201076;
disp('N = '); disp(mod(ID,3));

[A,p1] = lcgg(M,30269,171,0,1);
[B,p2] = lcgg(M,30307,172,0,1);
[C,p3] = lcgg(M,30323,170,0,1);

disp('Period = '); disp(p2);

% Combine the 3 generators as in Wichmann and Hill

figure(1);
subplot(2,1,1);hist(B);title('Histogram for Uniform RDN from LCG');
subplot(2,1,2);qqplot(rand(300,1),B);title('QQplot for uniform RDN from LCG');

figure(2);
scatter(B(1:(M-1),1),B(2:M,1),4);title('Plot of sequential pairs for LCG');

D = A + B + C - fix(A + B + C); % internal Matlab uniform random number generator

u = rand(M,1); % internal Matlab uniform random number generator

figure(3);
subplot(2,1,1);scatter(u(1:(M-1),1),u(2:M,1),4);title('Plot of Sequential Pairs for Matlab Internal Generator');
subplot(2,1,2);scatter(D(1:M-1),1),D(2:M,1),4;title('Plot of sequential pairs for 3 LCG Combined')



% Calculate the period
i = 1;
j = 2;
while A(i,1) ~= A(j,1) && i < m
    if j < m
        j = j+1;
    else
        i = i+1;
        j = j+1;
    end
end
if i == m
    p = m;
else
    p = j-1;
end
A = A./m;
if M <= m
    A = A(1:M,:);
end

function[A,p] = lcgg(M,m,a,c,x0)
% Generates a matrix of random numbers using lcg
% Calculate the period
% Input: M: total number of random numbers needed
%         m, a, x, x0
% Output: A: M * 1 matrix of random numbers
%         p: period of the LCG random number generator
    A = zeros(m,1);
    for i = 1:m
        if i == 1
            A(i,1) = lcg(m,a,c,x0);
        else
            A(i,1) = lcg(m,a,c,A(i-1,1));
        end
    end 
end

% The LCG Function:

function[x] = lcg(m,a,c,x0)
    % Linear Congruential Generator (LCG)
    x = mod(a*x0+c, m);
end

【参考方案1】：

你定义一个函数：

function[A,p] = lcgg(...)

在函数体中，您需要为A 和p 这两个输出变量赋值。您没有将任何内容分配给 p，因此是消息。

【讨论】：

啊，谢谢！一旦我将周期计算移到 lcgg 函数中，它就起作用了。