iamax (USM Version)¶
Finds the index of the element with the largest absolute value in a vector.
Description¶
The iamax
routines return an index i
such that x
[i
]
has the maximum absolute value of all elements in vector x
(real
variants), or such that |Re(x[i])| + |Im(x[i])|
is maximal
(complex variants).
Note
The index is zero-based.
If either n
or incx
are not positive, the routine returns 0
.
If more than one vector element is found with the same largest absolute value, the index of the first one encountered is returned.
If the vector contains NaN
values, then the routine returns the
index of the first NaN
.
API¶
Syntax¶
namespace oneapi::mkl::blas::column_major {
sycl::event iamax(sycl::queue &queue,
std::int64_t n,
const T *x,
std::int64_t incx,
T_res *result,
const std::vector<sycl::event> &dependencies = {})
}
namespace oneapi::mkl::blas::row_major {
sycl::event iamax(sycl::queue &queue,
std::int64_t n,
const T *x,
std::int64_t incx,
T_res *result,
const std::vector<sycl::event> &dependencies = {})
}
The USM version of iamax
supports the following precisions and devices:
T |
Devices Supported |
---|---|
|
Host, CPU, and GPU |
|
Host, CPU, and GPU |
|
Host, CPU, and GPU |
|
Host, CPU, and GPU |
Input Parameters¶
- exec_queue
The queue where the routine should be executed.
- n
The number of elements in vector
x
.- x
The pointer to the input vector
x
. The array holding the input vectorx
must be of size at least (1 + (n
- 1)*abs(incx
)). See Matrix and Vector Storage for more details.- incx
The stride of vector
x
.- dependencies
List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.
Output Parameters¶
- result
The pointer to where the zero-based index
i
of the maximal element is stored.
Return Values¶
Output event to wait on to ensure computation is complete.