trace:
  description: |
    Returns a new tensor that is the sum of the `input` main trace.

    Note:
        Input must be matrix, and complex number is not supported at present.

    Args:
        input (Tensor): A matrix to be calculated. The matrix must be two dimensional.

    Returns:
        Tensor, with the same data type as input `input`, and size equals to 1.

    Raises:
        TypeError: If `input` is not a Tensor.
        ValueError: If the dimension of `input` is not equal to 2.

    Supported Platforms:
        ``Ascend`` ``GPU`` ``CPU``

    Examples:
        >>> import mindspore
        >>> import numpy as np
        >>> from mindspore import Tensor, ops
        >>> input = Tensor(np.array([[10, 11, 12], [13, 14, 15], [16, 17, 18]]), mindspore.float32)
        >>> output = ops.trace(input)
        >>> print(output)
        42.0
        >>> input = Tensor(np.arange(1, 13).reshape(3, 4), mindspore.float32)
        >>> output = ops.trace(input)
        >>> print(output)
        18.0
        >>> input = Tensor(np.arange(12, 0, -1).reshape(4, 3), mindspore.float32)
        >>> output = ops.trace(input)
        >>> print(output)
        24.0