iamax¶
Finds the index of the element with the largest absolute value in a vector.
Syntax
void iamax(queue &exec_queue, std::int64_t n, buffer<T, 1> &x, std::int64_t incx, buffer<std::int64_t, 1> &result)
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 |
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
.
Input Parameters
- exec_queue
The queue where the routine should be executed.
- n
The number of elements in vector
x
.- x
The buffer that holds the input vector
x
. The buffer 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
.
Output Parameters
- result
The buffer where the zero-based index
i
of the maximal element is stored.
Example
An example of how to use iamax
can be found in the Intel® oneMKL
installation directory, under:
examples/dpcpp/blas/source/iamax.cpp