Fritsch F N (1982) PCHIP final specifications Report UCID-30194 Lawrence Livermore National Laboratory
1: – IntegerInput
2: – Real (Kind=nag_wp) arrayInput
3: – Real (Kind=nag_wp) arrayInput
4: – Real (Kind=nag_wp) arrayInput
On entry: n, x, f and d must be unchanged from the previous call of e01bef.
5: – Real (Kind=nag_wp)Input
6: – Real (Kind=nag_wp)Input
On entry: the interval over which integration is to be performed.
7: – Real (Kind=nag_wp)Output
On exit: the value of the definite integral of the interpolant over the interval .
8: – IntegerInput/Output
On entry: ifail must be set to , or to set behaviour on detection of an error; these values have no effect when no error is detected.
A value of causes the printing of an error message and program execution will be halted; otherwise program execution continues. A value of means that an error message is printed while a value of means that it is not.
If halting is not appropriate, the value or is recommended. If message printing is undesirable, then the value is recommended. Otherwise, the value is recommended. When the value or is used it is essential to test the value of ifail on exit.
On exit: unless the routine detects an error or a warning has been flagged (see Section 6).
6Error Indicators and Warnings
If on entry or , explanatory error messages are output on the current error message unit (as defined by x04aaf).
Errors or warnings detected by the routine:
On entry, .
On entry, , and .
Constraint: for all .
Warning – either a or b is outside the range . The result has been computed by extrapolation and is unreliable. .
An unexpected error has been triggered by this routine. Please
See Section 7 in the Introduction to the NAG Library FL 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 FL Interface for further information.
Dynamic memory allocation failed.
See Section 9 in the Introduction to the NAG Library FL Interface for further information.
The computational error in the value returned for pint should be negligible in most practical situations.
8Parallelism and Performance
e01bhf is not threaded in any implementation.
The time taken by e01bhf is approximately proportional to the number of data points included within the interval .
This example reads in values of n, x, f and d. It then reads in pairs of values for a and b, and evaluates the definite integral of the interpolant over the interval until end-of-file is reached.