Hi all,

I am trying to do inference for my model in C++ using Libtorch.

Following is the code which I am using.

```
torch::Tensor inputs = torch::zeros({in_1.size()*2, 1, 2}, torch::dtype(torch::kFloat32));
int i = 0;
const cellList &cells = mesh.cells();
forAll(cells, celli)
{
inputs[i][0][0] = in_1[celli];
inputs[i][0][1] = in_2[celli];
i = i + 1;
}
at::Tensor output_real = torch::zeros({in_1.size()*2,1,7}, torch::dtype(torch::kFloat32));
std::vector<torch::jit::IValue> input;
//* * * * * * * Inference * * * * * * * *//
for(int j = 0; j<i; j++)
{
input.push_back(inputs[j]);
output_real[j] = module->forward(input).toTensor();
input.clear();
}
std::cout<<"Inference has been completed"<<'\n';
int j = 0;
forAll(cells, celli)
{
if(j != i){
out_1[celli] = output_real[j][0][celli * 7];
out_2[celli] = output_real[j][0][celli * 7 + 1];
out_3[celli] = output_real[j][0][celli * 7 + 2];
out_4[celli] = output_real[j][0][celli * 7 + 3];
out_5[celli] = output_real[j][0][celli * 7 + 4];
out_6[celli] = output_real[j][0][celli * 7 + 5];
out_7[celli] = output_real[j][0][celli * 7 + 6];
}
j = j+1;
}
```

in this code neural network’s input is `1x2`

dim and output is `1x7`

.

Now the problem is in the last loop it gives error of type conversion which is as follows:

```
inferFoam.C: In function ‘int main(int, char**)’:
inferFoam.C:95:46: error: cannot convert ‘at::Tensor’ to ‘double’ in assignment
out_1[celli] = output_real[j][0][celli * 7];
^
inferFoam.C:96:59: error: cannot convert ‘at::Tensor’ to ‘double’ in assignment
out_2[celli] = output_real[j][0][celli * 7 + 1];
^
inferFoam.C:97:59: error: cannot convert ‘at::Tensor’ to ‘double’ in assignment
out_3[celli] = output_real[j][0][celli * 7 + 2];
^
inferFoam.C:98:59: error: cannot convert ‘at::Tensor’ to ‘double’ in assignment
out_4[celli] = output_real[j][0][celli * 7 + 3];
^
inferFoam.C:99:50: error: cannot convert ‘at::Tensor’ to ‘double’ in assignment
out_5[celli] = output_real[j][0][celli * 7 + 4];
^
inferFoam.C:100:56: error: cannot convert ‘at::Tensor’ to ‘double’ in assignment
out_6[celli] = output_real[j][0][celli * 7 + 5];
^
inferFoam.C:101:56: error: cannot convert ‘at::Tensor’ to ‘double’ in assignment
out_7[celli] = output_real[j][0][celli * 7 + 6];
^
```

I tried explicit conversion like `(double)output_real[j][0][celli * 7 + 5]`

but it doesn’t seem to work and says:

```
error: invalid cast from type ‘at::Tensor’ to type ‘double’
std::cout << (double)output[i][0][1] << '\n';
^
```

Can anybody please tell me what’s the solution to this problem is?

Secondly, I am confused that, earlier in the first loop when I am reading the input values from `in_1[celli]`

and `in_2[celli]`

into `inputs`

it doesn’t give this kind of (type conversion) error there even though there also I am doing the same thing; exchanging two different datatypes.

Can anybody tell me please what’s seems to the problem, what is my mistake and also please suggest a solution.

Regards.