matrix multiply another matrix by *

in .* and .^, "." -- dot means compute elements, one by one. "^2" means squaring

get 绝对值

plus one for all elements in a vector

another way to do this

trans the matrix by '

find max of a matrix

the 3rd param is which dimension you want to find the max. 1 means max of each column. 2 means max of each row.

max(A) is same as max(A,[],1]

if you want to find max elements in this matrix then you need to call max 2 times:

max(max(A))

or max(A(:)) A(:) will make all of them into a vector

same as other functions like size and max, sum will sum each columns, same as sum(A,1).

sum(A,2) will sum each row.

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