trace

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trace#

class saiunit.math.trace(a, offset=0, axis1=0, axis2=1, dtype=None, **kwargs)#

Return the sum along diagonals of the array.

If a is 2-D, the sum along its diagonal with the given offset is returned, i.e., the sum of elements a[i,i+offset] for all i.

If a has more than two dimensions, then the axes specified by axis1 and axis2 are used to determine the 2-D sub-arrays whose traces are returned. The shape of the resulting array is the same as that of a with axis1 and axis2 removed.

Parameters:

  • a (Array | saiunit.Quantity) – Input array, from which the diagonals are taken.

  • offset (int) – Offset of the diagonal from the main diagonal. Can be both positive and negative. Defaults to 0.

  • axis1 (int) – Axes to be used as the first and second axis of the 2-D sub-arrays from which the diagonals should be taken. Defaults are the first two axes of a.

  • axis2 (int) – Axes to be used as the first and second axis of the 2-D sub-arrays from which the diagonals should be taken. Defaults are the first two axes of a.

  • dtype (str | type[Any] | dtype | SupportsDType | None) – Determines the data-type of the returned array and of the accumulator where the elements are summed. If dtype has the value None and a is of integer type of precision less than the default integer precision, then the default integer precision is used. Otherwise, the precision is the same as that of a.

Returns:

sum_along_diagonals – If a is 2-D, the sum along the diagonal is returned. If a has larger dimensions, then an array of sums along diagonals is returned.

This is a Quantity if a is a Quantity, else an array.

Return type:

Array | saiunit.Quantity

Examples

>>> import saiunit as u
>>> a = [[1, 2], [3, 4]] * u.second
>>> u.math.trace(a)
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