How do you pass two arrays to a function so that the function can copy one
to the other, and return the values in place? Of course, a=b won't work,
but neither does a=copy(b). See the following example:
julia> function copytest!(a,b)
b=copy(a)
println ("copytest: a,b ",a,b)
nothing
end
copytest! (generic function with 1 method)
julia> a=ones(2,2)
2x2 Array{Float64,2}:
1.0 1.0
1.0 1.0
julia> b=zeros(2,2)
2x2 Array{Float64,2}:
0.0 0.0
0.0 0.0
julia> copytest!(a,b)
copytest: a,b [1.0 1.0
1.0 1.0][1.0 1.0
1.0 1.0]
julia> println ("copytest: a,b ",a,b)
copytest: a,b [1.0 1.0
1.0 1.0][0.0 0.0
0.0 0.0]
The first println shows that b WAS changed inside the copytest function.
The second println shows that it WASN'T changed on return. I've also tried
with do loops, but this causes a segmentation fault.
