Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

ID 766686
Date 6/24/2024
Public

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?lasrt2

Sorts numbers in increasing or decreasing order.

Syntax

call slasrt2(id, n, d, key, info)

call dlasrt2(id, n, d, key, info)

Description

The ?lasrt2routine is modified LAPACK routine ?lasrt, which sorts the numbers in d in increasing order (if id = 'I') or in decreasing order (if id = 'D' ). It uses Quick Sort, reverting to Insertion Sort on arrays of size 20. The size of STACK limits n to about 232.

Input Parameters

id

CHARACTER*1.

= 'I': sort d in increasing order;

= 'D': sort d in decreasing order.

n

INTEGER. The length of the array d.

d

REAL for slasrt2

DOUBLE PRECISION for dlasrt2.

Array of size n.

On entry, the array to be sorted.

key

INTEGER.

Array of size n.

On entry, key contains a key to each of the entries in d().

Typically, key(i) = i for all i.

Output Parameters

d

On exit, d has been sorted into increasing order

(d(1) ... d(n) )

or into decreasing order

(d(1) ... d(n) ),

depending on id.

info

INTEGER.

= 0: successful exit

< 0: if info = -i, the i-th argument had an illegal value.

key

On exit, key is permuted in exactly the same manner as d was permuted from input to output. Therefore, if key(i) = i for all i on input, d(i) on output equals d(key(i)) on input.

See Also