When I tried to estimate the output size of conv layer using the formula in the doc,

the number I got from the formula is actually different from what I get from the layer.
for the 2d input of size (101, 40)
with kernel(16,8), stride (2,1) padding (0,0), dilation (1,1),
torch.2dconv generates (43,33)
while formula seems to give (44,33)
where is this mismatch coming from?
Also I tried to understand the formula but couldn’t figure out where the last -1 operation comes from.
we should be following basic math ordering (Brackets, Orders, Division and Multiplication, and Addition and Subtraction) here right?
Can anyone clarify?