# prod!

prod!(r, A)

Multiply elements of `A` over the singleton dimensions of `r`, and write results to `r`.

## Examples

``````julia> r = [1, 1, 1];
julia> A = [2, 3, 4];
julia> prod!(r, A)
3-element Array{Int64,1}:
2
3
4``````

This example multiplies the elements of array `A` over the singleton dimensions of array `r` and assigns the results to `r`.

``````julia> r = [1, 1, 1];
julia> A = [2 3 4];
julia> prod!(r, A)
3-element Array{Int64,1}:
24
1
1``````

In this example, `A` is a matrix with dimensions (1, 3). The `prod!` function multiplies the elements of `A` along the singleton dimension and stores the results in `r`.

``````julia> r = [1, 1];
julia> A = [2, 3, 4];
julia> prod!(r, A)
2-element Array{Int64,1}:
6
4``````

Here, `A` is a 1-dimensional array of length 3. The `prod!` function multiplies the elements of `A` and stores the results in `r`.

Common mistake example:

``````julia> r = [1, 1, 1];
julia> A = [2, 3, 4, 5];
julia> prod!(r, A)
ERROR: DimensionMismatch("arrays could not be broadcast to a common size")``````

In this example, the dimensions of `r` and `A` do not match, causing a `DimensionMismatch` error. Ensure that the dimensions of the input arrays are compatible to avoid such errors when using `prod!`.