add min_all and max_all to tensor (#86)

Co-authored-by: mp <pro@macbookpro>

Author: AlpineVibrations

candle-core/src/tensor.rs

@@ -1749,6 +1749,42 @@ impl Tensor {
         &self.op
     }
 
+    /// Computes the max of all the elements in this tensor and returns a tensor holding this
+    /// scalar with zero dimensions.
+    ///
+    /// ```rust
+    /// use candle_core::{Tensor, Device};
+    /// let tensor = Tensor::new(&[[0f32, 1.], [2., 3.], [4., 5.]], &Device::Cpu)?;
+    /// let tensor = tensor.max_all()?;
+    /// assert_eq!(tensor.to_scalar::<f32>()?, 5.);
+    /// # Ok::<(), candle_core::Error>(())
+    /// ```
+    pub fn max_all(&self) -> Result<Tensor> {
+        if self.rank() == 0 {
+            Ok(self.clone())
+        } else {
+            self.flatten_all()?.max(0)
+        }
+    }
+
+    /// Computes the min of all the elements in this tensor and returns a tensor holding this
+    /// scalar with zero dimensions.
+    ///
+    /// ```rust
+    /// use candle_core::{Tensor, Device};
+    /// let tensor = Tensor::new(&[[0f32, 1.], [2., 3.], [4., 5.]], &Device::Cpu)?;
+    /// let tensor = tensor.min_all()?;
+    /// assert_eq!(tensor.to_scalar::<f32>()?, 0.);
+    /// # Ok::<(), candle_core::Error>(())
+    /// ```
+    pub fn min_all(&self) -> Result<Tensor> {
+        if self.rank() == 0 {
+            Ok(self.clone())
+        } else {
+            self.flatten_all()?.min(0)
+        }
+    }
+
     /// Computes the sum of all the elements in this tensor and returns a tensor holding this
     /// scalar with zero dimensions.
     ///