# scale!

``````..  scale!(A, b)
scale!(b, A)

Scale an array ``A`` by a scalar ``b``, similar to :func:`scale` but
overwriting ``A`` in-place.

If ``A`` is a matrix and ``b`` is a vector, then ``scale!(A,b)``
scales each column ``i`` of ``A`` by ``b[i]`` (similar to
``A*diagm(b)``), while ``scale!(b,A)`` scales each row ``i`` of
``A`` by ``b[i]`` (similar to ``diagm(b)*A``), again operating in-place
on ``A``.``````

## Examples

The `scale!` function in Julia scales an array `A` by a scalar `b` in-place. It can be used to scale both vectors and matrices. Here are some examples of how to use the `scale!` function:

1. Scale a vector in-place:

``````julia> v = [1, 2, 3, 4];
julia> scale!(v, 2);
julia> v
4-element Array{Int64,1}:
2
4
6
8``````

This example scales each element of the vector `v` by the scalar value 2.

2. Scale each column of a matrix by a vector:

``````julia> A = [1 2 3; 4 5 6; 7 8 9];
julia> b = [2, 3, 4];
julia> scale!(A, b);
julia> A
3×3 Array{Int64,2}:
2   4   6
12  15  18
28  32  36``````

In this example, the `scale!` function scales each column of matrix `A` by the corresponding element of vector `b`.

3. Scale each row of a matrix by a vector:
``````julia> A = [1 2 3; 4 5 6; 7 8 9];
julia> b = [2, 3, 4];
julia> scale!(b, A);
julia> A
3×3 Array{Int64,2}:
2   4   6
12  15  18
28  32  36``````

This example scales each row of matrix `A` by the corresponding element of vector `b`.

Note: The `scale!` function modifies the input array in-place, meaning the original array is overwritten with the scaled values.

If there are any mistakes made while using the `scale!` function, it is usually related to passing arrays of incompatible sizes. Make sure the dimensions of the array and scalar/vector match appropriately.