Dilated convolutions (#657)

* Add the dilation parameter.

* Restore the basic optimizer example.

* Dilation support in cudnn.

* Use the dilation parameter in the cpu backend.

* More dilation support.

* No support for dilation in transposed convolutions.

* Add dilation to a test.

* Remove a print.

* Helper function.

candle-core/src/device.rs

@@ -81,6 +81,26 @@ impl<S: WithDType, const N1: usize, const N2: usize, const N3: usize> NdArray
     }
 }
 
+impl<S: WithDType, const N1: usize, const N2: usize, const N3: usize, const N4: usize> NdArray
+    for &[[[[S; N4]; N3]; N2]; N1]
+{
+    fn shape(&self) -> Result<Shape> {
+        Ok(Shape::from((N1, N2, N3, N4)))
+    }
+
+    fn to_cpu_storage(&self) -> CpuStorage {
+        let mut vec = Vec::with_capacity(N1 * N2 * N3 * N4);
+        for i1 in 0..N1 {
+            for i2 in 0..N2 {
+                for i3 in 0..N3 {
+                    vec.extend(self[i1][i2][i3])
+                }
+            }
+        }
+        S::to_cpu_storage_owned(vec)
+    }
+}
+
 impl Device {
     pub fn new_cuda(ordinal: usize) -> Result<Self> {
         Ok(Self::Cuda(crate::CudaDevice::new(ordinal)?))