matlab中sum函数

matlab中sum函数

下面是matlab中sum函数的代码，可以看出里面也是用for循环实现的~~function s = sum(A,dim)%SUM Sum of the elements.% For vectors, SUM(X) is the sum of the elements of X.% For matrices, SUM(X) or SUM(X,1) is a row vector of column sums% and SUM(X,2) is a column vector of row sums.%% See also SYM/PROD. % Copyright 1993-2008 The MathWorks, Inc.if isscalar(A) && strcmp(class(A.s),'maplesym') if nargin == 1 s = sym(sum(A.s)); else s = sym(sum(A.s,dim)); endelseif nargin == 1 && any(size(A) == 1) s = sym(0); for k = 1:numel(A) s = s + A(k); endelseif nargin == 1 || dim == 1 s = sym(zeros(1,size(A,2))); for i = 1:size(A,1) s = s + A(i,:); endelse s = sym(zeros(size(A,1),1)); for j = 1:size(A,2); s = s + A(:,j); endend