The NAG error argument (see Section 7 in the Introduction to the NAG Library CL Interface).
6Error Indicators and Warnings
Dynamic memory allocation failed.
See Section 3.1.2 in the Introduction to the NAG Library CL Interface for further information.
On entry, argument had an illegal value.
On entry, a, b, c, or d is not in the allowed range: , , and .
The algorithm for computing eigenvalues of a tridiagonal matrix has failed to converge.
The contribution of the central abscissa to the summation
On entry, .
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.
See Section 7.5 in the Introduction to the NAG Library CL Interface for further information.
Your licence key may have expired or may not have been installed correctly.
See Section 8 in the Introduction to the NAG Library CL Interface for further information.
One or more of the weights are larger than , the largest floating point number on this computer (see X02ALC): . Possible solutions are to use a smaller value of ; or, if using adjusted weights to change to normal weights.
One or more of the weights are too small to be distinguished from zero on this machine. The underflowing weights are returned as zero, which may be a usable approximation. Possible solutions are to use a smaller value of ; or, if using normal weights, to change to adjusted weights.
The accuracy depends mainly on , with increasing loss of accuracy for larger values of . Typically, one or two decimal digits may be lost from machine accuracy with , and three or four decimal digits may be lost for .
8Parallelism and Performance
d01tcc makes calls to BLAS and/or LAPACK routines, which may be threaded within the vendor library used by this implementation. Consult the documentation for the vendor library for further information.
Please consult the X06 Chapter Introduction for information on how to control and interrogate the OpenMP environment used within this function. Please also consult the Users' Note for your implementation for any additional implementation-specific information.
The major portion of the time is taken up during the calculation of the eigenvalues of the appropriate tridiagonal matrix, where the time is roughly proportional to .
This example returns the abscissae and (adjusted) weights for the seven-point Gauss–Laguerre formula.