Matlab pcg函数的句柄形式之参数传递

求解线性方程组 - 预条件共轭梯度法 - MATLAB pcg - MathWorks 中国
https://ww2.mathworks.cn/help/matlab/ref/pcg.html

PCG on a large sparse matrix from Finite difference method - MATLAB Answers - MATLAB Central
https://ww2.mathworks.cn/matlabcentral/answers/407845-pcg-on-a-large-sparse-matrix-from-finite-difference-method

 方法一：全局变量法-不推荐

clc;clear
n=10;
global A
A = sprand(n,n,0.5);  % Sparse matrix with density 0.5
A = A'*A;
b=eye(10,1)
[x3] = pcg(@afun,b,1e-8,100)


function y=afun(x)
    global A
    y=A*x;
end

 方法二：匿名函数法-推荐

clc;clear
n = 20;
A = gallery('tridiag',ones(n-1,1),n:-1:1,ones(n-1,1));
B= gallery('tridiag',ones(n-1,1),n:-1:1,ones(n-1,1));
b = ones(20,1);
myA = @(x) afun(x,A,B);
x1 = pcg(myA,b)

function y = afun(x,A,B)
y=A(B*x);
end