add max_pool2d (#371)

Co-authored-by: 赵理山 <ls@zhaolishandeMacBook-Air.local>

candle-core/tests/pool_tests.rs

@@ -14,6 +14,18 @@ fn avg_pool2d() -> anyhow::Result<()> {
     Ok(())
 }
 
+#[test]
+fn max_pool2d() -> anyhow::Result<()> {
+    let data: Vec<f32> = vec![
+        1., 2., 1., 3., 0., 0., 1., 1., 1., 1., 1., 1., 5., 1., 1., 1.,
+    ];
+    let t = Tensor::from_vec(data, (1, 1, 4, 4), &Device::Cpu)?;
+
+    let pool = t.max_pool2d((2, 2), (2, 2))?.squeeze(0)?.squeeze(0)?;
+    assert_eq!(pool.to_vec2::<f32>()?, [[2f32, 3.], [5., 1.]]);
+    Ok(())
+}
+
 /* This test corresponds to the following PyTorch script.
 import torch
 torch.manual_seed(4242)