Taking variable as independent with Zygote (Automatic differentiation)

General Usage
,
1

I have a function that I want to take the gradient of in the end. I want to achive that a certain variable is deemed independent of the variable i wish to differentiate in the the end. I tried to do this with the Zygote.ignore() function but this does not seem to work:

function test(A)
    Zygote.ignore() do
        B = A
    end
    c = norm(A*B)
return c
end

A = rand(5,5)
test(A)

Here I would in the end take the gradient with respect to A…
This seems to create B only as a local variable within the “do-Block”. Is there a way around this?

2 
function test(A)
    B = Zygote.@ignore A
    norm(A * B)
end