Mapping vector elements

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1

Hi, I am defining the gradients by using below code but i want to make negative values to zero. I wrote below code but it is not working. could you please help me to modify this

function gf_p(p0::Vector, grad::Vector; r, β, η, fem_params)
    if length(grad) > 0
        dgdp, = Zygote.gradient(p -> gf_p(p; r, β, η, fem_params), p0)
        grad[:] = dgdp
    end
    map(x-> grad[:]<0 , 0)
    -grad
end

thank you

2

Among other oddities, you’re discarding the value of this expression.

3

One way to set negative values to zero is with the code

x[x .< 0] .= 0

map on its own will not modify the values in place.

2 Likes
4

thank you very much! it is working.

5

You could also do

x .= max.(x, 0)

which should be faster, since it doesn’t create any temporary array.

And this

should probably be replaced with

grad .= dgdp

Actually, why do you need to modify grad? Isn’t it better to just work on dgdp without copying the data into grad?

6

what do you mean by modifying dgdp? It seems that there are some errors in calculating the gradients by zygot and they are very small so i want to make them as zero.