# 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

1. 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].

2. Calculate the 1-norm of a matrix:

``````julia> mat = [1 2; -3 4];
julia> vecnorm(mat, 1)
5.0``````

It computes the 1-norm (sum of absolute values) of the matrix `mat` treating it as a vector.

3. 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.

4. 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 p-norm: -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,

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