class_docstr: The Exponential kernel. It is equivalent to a Matern12 kernel with doubled lengthscales.
class_docstr_tok: ["The","Exponential","kernel",".","It","is","equivalent","to","a","Matern12","kernel","with","doubled","lengthscales","."]
code: def K_r(self, r: TensorType) -> tf.Tensor:
      return self.variance * tf.exp(-0.5 * r)
  
imports: from typing import Any, Optional
  import numpy
  import tensorflow
  from check_shapes import check_shapes, inherit_check_shapes
  from ..base import Parameter, TensorType
  from ..utilities import positive
  from ..utilities.ops import difference_matrix, square_distance
  from .base import ActiveDims, Kernel
label_desc: Use image node_id 1 for calling the Exponential obj's underlying member method code with example usage: obj.K_r(r) and returns: unknown