nag_dge_load (f16qhc) (PDF version)
f16 Chapter Contents
f16 Chapter Introduction
NAG Library Manual

NAG Library Function Document

nag_dge_load (f16qhc)

+ Contents

    1  Purpose
    7  Accuracy

1  Purpose

nag_dge_load (f16qhc) initializes a real general matrix.

2  Specification

#include <nag.h>
#include <nagf16.h>
void  nag_dge_load (Nag_OrderType order, Integer m, Integer n, double alpha, double diag, double a[], Integer pda, NagError *fail)

3  Description

nag_dge_load (f16qhc) forms the real m by n general matrix A given by
aij= d if i=j α if ij .

4  References

Basic Linear Algebra Subprograms Technical (BLAST) Forum (2001) Basic Linear Algebra Subprograms Technical (BLAST) Forum Standard University of Tennessee, Knoxville, Tennessee

5  Arguments

1:     orderNag_OrderTypeInput
On entry: the order argument specifies the two-dimensional storage scheme being used, i.e., row-major ordering or column-major ordering. C language defined storage is specified by order=Nag_RowMajor. See Section in the Essential Introduction for a more detailed explanation of the use of this argument.
Constraint: order=Nag_RowMajor or Nag_ColMajor.
2:     mIntegerInput
On entry: m, the number of rows of the matrix A.
Constraint: m0.
3:     nIntegerInput
On entry: n, the number of columns of the matrix A.
Constraint: n0.
4:     alphadoubleInput
On entry: the value, α, to be assigned to the off-diagonal elements of A.
5:     diagdoubleInput
On entry: the value, d, to be assigned to the diagonal elements of A.
6:     a[dim]doubleOutput
Note: the dimension, dim, of the array a must be at least
  • max1,pda×n when order=Nag_ColMajor;
  • max1,m×pda when order=Nag_RowMajor.
If order=Nag_ColMajor, Aij is stored in a[j-1×pda+i-1].
If order=Nag_RowMajor, Aij is stored in a[i-1×pda+j-1].
On exit: the m by n general matrix A.
7:     pdaIntegerInput
On entry: the stride separating row or column elements (depending on the value of order) of the matrix A in the array a.
Constraint: pdamax1,m.
8:     failNagError *Input/Output
The NAG error argument (see Section 3.6 in the Essential Introduction).

6  Error Indicators and Warnings

Dynamic memory allocation failed.
On entry, argument value had an illegal value.
On entry, m=value.
Constraint: m0.
On entry, n=value.
Constraint: n0.
On entry, pda=value.
Constraint: pdamax1,m.
On entry, pda=value.
Constraint: pdamax1,n.
On entry, pda=value, m=value.
Constraint: pdamax1,m.
An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact NAG for assistance.

7  Accuracy

The BLAS standard requires accurate implementations which avoid unnecessary over/underflow (see Section 2.7 of Basic Linear Algebra Subprograms Technical (BLAST) Forum (2001)).

8  Parallelism and Performance

Not applicable.

9  Further Comments


10  Example

This example initializes a real general matrix, A, with diagonal off-diagonal value, α=1.23 and diagonal value, d=3.45.

10.1  Program Text

Program Text (f16qhce.c)

10.2  Program Data

Program Data (f16qhce.d)

10.3  Program Results

Program Results (f16qhce.r)

nag_dge_load (f16qhc) (PDF version)
f16 Chapter Contents
f16 Chapter Introduction
NAG Library Manual

© The Numerical Algorithms Group Ltd, Oxford, UK. 2014