vecnorm
vecnorm(A, [p])
For any iterable container A
(including arrays of any dimension) of numbers (or any element type for which norm
is defined), compute the p
norm (defaulting to p=2
) as if A
were a vector of the corresponding length.
For example, if A
is a matrix and p=2
, then this is equivalent to the Frobenius norm.
Examples

Compute the Euclidean norm of a vector:
julia> vecnorm([3, 4]) 5.0
This example calculates the Euclidean norm (p=2 norm) of the vector [3, 4].

Calculate the 1norm of a matrix:
julia> mat = [1 2; 3 4]; julia> vecnorm(mat, 1) 5.0
It computes the 1norm (sum of absolute values) of the matrix
mat
treating it as a vector. 
Calculate the infinity norm of a matrix:
julia> mat = [1 2; 3 4]; julia> vecnorm(mat, Inf) 7.0
This example computes the infinity norm (maximum absolute row sum) of the matrix
mat
as if it were a vector.  Compute the Frobenius norm of a matrix:
julia> mat = [1 2; 3 4]; julia> vecnorm(mat) 5.477225575051661
It calculates the Frobenius norm (p=2 norm) of the matrix
mat
.
Common mistake example:
julia> vecnorm([1, 2, 3], 1)
ERROR: ArgumentError: Invalid value for pnorm: 1
In this example, 1
is provided as the p
value, which is not a valid input. The p
value should be a positive number or Inf
.
See Also
countfrom, cycle, done, drop, eachindex, enumerate, first, repeated, rest, start, svds, take, vecdot, vecnorm, zip,User Contributed Notes
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