matlab中norm的用法_matlab的norm-MATLAB norm

matlab中norm的用法_matlab的normMatlabnorm用法小记matlabnorm(a)用法以及实例norm(A,p)当A是向量时norm(A,p)Returnssum(abs(A).^p)^(1/p),forany1<=p<=∞.norm(A)Returnsnorm(A,2)norm(A,inf)Returnsmax(abs(A)).norm(A,-inf)…

Matlab norm 用法小记

matlab norm (a) 用法以及实例

norm(A,p)
当A是向量时
norm(A,p) Returns sum(abs(A).^p)^(1/p), for any 1 <= p <= ∞.
norm(A) Returns norm(A,2)
norm(A,inf) Returns max(abs(A)).
norm(A,-inf) Returns min(abs(A)).

当A是矩阵时
n = norm(A) returns the largest singular value of A, max(svd(A))
n = norm(A,1) The 1-norm, or largest column sum of A, max(sum(abs(A)).
n = norm(A,2) The largest singular value (same as norm(A)).
n = norm(A,inf) The infinity norm, or largest row sum of A, max(sum(abs(A’)))
n = norm(A,’fro’) The Frobenius-norm of matrix A, sqrt(sum(diag(A’*A))).

norm

Vector and matrix norms

Syntax

n = norm(A)n = norm(A,p)

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Description

Thenormof a matrix is a scalar that gives some measure of the magnitude of the elements of the matrix. Thenormfunction calculates several different types of matrix norms:

n = norm(A)returns the largest singular value ofA,max(svd(A)).

n = norm(A,p)returns a different kind of norm, depending on the value ofp.

WhenAis a vector:

Remarks

Note thatnorm(x)is the Euclidean length of a vectorx. On the other hand, MATLAB uses “length” to denote the number of elementsnin a vector. This example usesnorm(x)/sqrt(n)to obtain theroot-mean-square (RMS) value of ann-element vectorx.

x = [0 1 2 3]x =      0     1     2     3sqrt(0+1+4+9)   % Euclidean lengthans =    3.7417norm(x)ans =    3.7417n = length(x)   % Number of elementsn =     4rms = 3.7417/2  % rms = norm(x)/sqrt(n)rms =    1.8708