Iamax

Applicable Products

Function Description

API function

• asdBlasMakeIamaxPlan: initializes the Iamax operator configuration corresponding to the handle.
• asdBlasIsamax: finds the element with the largest absolute value in the real vector and returns its index. If there are multiple equal elements, the smallest index is returned.
• asdBlasIcamax: finds the element with the largest sum of the absolute values of the imaginary and real parts in a complex vector and returns its index. If the sum of absolute values of multiple elements is equal, the index of the element that is found first is returned.

Formula:

• asdBlasIsamax formula:
  • Example:

    Input x:

    [3, 4, 4,3]

    After the Isamax operator is called, the output result is as follows:

    2

• asdBlasIcamax formula: ,

  where Re(x) represents a real part of a complex number, and Im(x) represents an imaginary part of the complex number.

  • Example:

    Input x:

    [3+4i,4-3i,4+2i,3-1i]

    After the Icamax operator is called, the output result is as follows:

    1

Function Prototype

• AspbStatus asdBlasMakeIamaxPlan(asdBlasHandle handle)
• AspbStatus asdBlasIcamax(asdBlasHandle handle, const int64_t n, aclTensor *x, const int64_t incx,aclTensor *result)
• AspbStatus asdBlasIsamax(asdBlasHandle handle, const int64_t n, aclTensor *x, const int64_t incx,aclTensor *result)

Parameter Description

• asdBlasMakeIamaxPlan

  Parameter	Input/Output	Type	Description
  handle	Input	asdBlasHandle	Handle of the Iamax operator.

• asdBlasIsamax & asdBlasIcamax

  Parameter	Input/Output	Type	Description
  handle	Input	asdBlasHandle	Handle of the Iamax operator.
  n	Input	const int64_t	Total number of elements.
  x	Input	aclTensor *	x in the formula, which is a tensor on the device. The data format can be ND, and the shape is [n]. For Isamax, the supported data type is FLOAT32. For Icamax, the supported data type is COMPLEX64.
  incx	Input	const int64_t	Memory address increment between consecutive elements of x (currently restricted to 1).
  result	Output	aclTensor *	result in the formula, which is a tensor on the device. The supported data type is INT32. It contains only one element. The data format supports ND, and the shape is [1].

Return Value Description

For details about the return values, see Return Value.

Constraints

• asdBlasMakeIamaxPlan: none.
• asdBlasIsamax
  • The input element count n currently supports the range [1, 6.71e+06].
  • The input shape of the operator is [n], and the output shape is [1].
  • The operator does not support the calculation for three or more dimensions.
• asdBlasIcamax
  • The input element count n currently supports the range [1, 6.71e+06].
  • The input shape of the operator is [n], and the output shape is [1].
  • The operator does not support the calculation for three or more dimensions.

Calling Example

For details about the operator calling example, see Iamax.