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! R8VEC_BRACKET searches a sorted R8VEC for successive brackets of a value.
Discussion:
An R8VEC is an array of double precision real values.
If the values in the vector are thought of as defining intervals
on the real line, then this routine searches for the interval
nearest to or containing the given value.
Licensing:
This code is distributed under the GNU LGPL license.
Modified:
06 April 1999
Author:
John Burkardt
Parameters:
Input, integer ( kind = 4 ) N, length of input array.
Input, real ( kind = 8 ) X(N), an array sorted into ascending order.
Input, real ( kind = 8 ) XVAL, a value to be bracketed.
Output, integer ( kind = 4 ) LEFT, RIGHT, the results of the search.
Either:
XVAL < X(1), when LEFT = 1, RIGHT = 2;
X(N) < XVAL, when LEFT = N-1, RIGHT = N;
or
X(LEFT) <= XVAL <= X(RIGHT).
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| integer(kind=4) | :: | n | ||||
| real(kind=8) | :: | x(n) | ||||
| real(kind=8) | :: | xval | ||||
| integer(kind=4) | :: | left | ||||
| integer(kind=4) | :: | right |