VALUE_LOCATE
Syntax | Return Value | Arguments | Keywords | Examples | Version History
The VALUE_LOCATE function finds the intervals within a given monotonic vector that brackets a given set of one or more search values. This function is useful for interpolation and table-lookup, and is an adaptation of the locate() routine in Numerical Recipes. VALUE_LOCATE uses the bisection method to locate the interval.
Syntax
Result = VALUE_LOCATE ( Vector, Value [, /L64 ] )
Return Value
Each return value, Result [i], is an index, j, into Vector, corresponding to the interval into which the given Value [i] falls. The returned values are in the range –1 ≤ j ≤ N–1, where N is the number of elements in the input vector.
If Vector is monotonically increasing, the result j is:
if j = –1 Value [i] < Vector [0]
if 0 ≤ j < N–1 Vector [j] ≤ Value [i] < Vector [j+1]
if j = N–1 Vector [N–1] ≤ Value [i]
If Vector is monotonically decreasing
if j = –1 Vector [0] ≤ Value [i]
if 0 ≤ j < N–1 Vector [j+1] ≤ Value [i] < Vector [j]
if j = N–1 Value [i] < Vector [N–1]
Arguments
Vector
A vector of monotonically increasing or decreasing values. Vector may be of type string, or any numeric type except complex, and may not contain the value NaN (not-a-number).
Value
The value for which the location of the intervals is to be computed. Value may be either a scalar or an array. The return value will contain the same number of elements as this parameter.
Keywords
L64
By default, the result of VALUE_LOCATE is 32-bit integer when possible, and 64-bit integer if the number of elements being processed requires it. Set L64 to force 64-bit integers to be returned in all cases.
Note
Only 64-bit versions of IDL are capable of creating variables requiring a 64-bit result. Check the value of !VERSION.MEMORY_BITS to see if your IDL is 64-bit or not.
Examples
IDL prints:
Version History
