Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
p?amax
Computes the global index of the element of a distributed vector with maximum absolute value.
Syntax
call psamax ( n , amax , indx , x , ix , jx , descx , incx )
call pdamax ( n , amax , indx , x , ix , jx , descx , incx )
call pcamax ( n , amax , indx , x , ix , jx , descx , incx )
call pzamax ( n , amax , indx , x , ix , jx , descx , incx )
Include Files
mkl_pblas.h
Description
The functions p?amax compute global index of the maximum element in absolute value of a distributed vector sub(x) ,
where sub(x) denotes X(ix, jx:jx+n-1) if incx=m_x , and X(ix: ix+n-1, jx) if incx= 1 .
Input Parameters
n
(global) INTEGER . The length of distributed vector sub(x) , n ≥ 0.
x
(local) REAL for psamax
DOUBLE PRECISION for pdamax COMPLEX for pcamax DOUBLE COMPLEX for pzamax Array, size (jx-1)*m_x + ix+(n-1)*abs(incx)) . This array contains the entries of the distributed vector sub(x) .
ix , jx
(global) INTEGER . The row and column indices in the distributed matrix X indicating the first row and the first column of the submatrix sub(X) , respectively.
descx
(global and local) INTEGER array of dimension 9. The array descriptor of the distributed matrix X .
incx
(global) INTEGER . Specifies the increment for the elements of sub(x) . Only two values are supported, namely 1 and m_x . incx must not be zero.
Output Parameters
amax
(global) REAL for psamax .
DOUBLE PRECISION for pdamax . COMPLEX for pcamax . DOUBLE COMPLEX for pzamax . Maximum absolute value (magnitude) of elements of the distributed vector only in its scope.
indx
(global) INTEGER . The global index of the maximum element in absolute value of the distributed vector sub(x) only in its scope.