can I set a device vector in a loop

[ztdepztdep]

I want to set the device vector like the c++ vector
for(int i=0;i<100;i++) device_vector[i]=3.14.

Does it works in thrust?

[miscco]

I would advice against that and instead either use the suitable constructor or thrust::fill in case of a constant input

[alliepiper]

@miscco is correct, it's better to do a bulk write into a device_vector instead of assigning each element.

Assigning in a loop will work, but it will be very slow and inefficient, as each individual element will be copied from host -> device memory in separate transactions. These copies are very expensive, and minimizing them using bulk update methods will improve performance significantly.

If each element has the same value (as in the example) the thrust::device_vector<float> data(100, 3.14f) constructor or thrust::fill(data.begin(), data.end(), 3.14f) will work, as mentioned above.

If the data is more complex, it's more efficient to create a thrust::host_vector with the data and then copy that into the thrust::device_vector:

thrust::host_vector<float> h_data;
// fill h_data
thrust::device_vector<float> d_data = h_data; // copies all data at once