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# number_merge(+List1, +List2, -List3)

Succeeds if List3 is a merged list of List1 and List2. If both lists are
sorted, List3 will be sorted.
*List1*
- List of numeric terms.
*List2*
- List of numeric terms.
*List3*
- List of numeric terms or variable.

## Description

Used to merge the sorted lists List1 and List2 to give the sorted list
List3.
For two lists [e1,e2,e3] and [f1,f2,f3], e1 is compared to f1. The
lower (dictated by numerical ordering) is put into List3, and the
process continued with the remaining input lists. This process
continues until both lists are exhausted.

In particular, this will merge two sorted lists into a sorted list.

The sort is done according to numerical ordering of terms as opposed to
merge/3 which uses the standard ordering of terms. Duplicates are
not removed. See sort/4 for a discussion of the differences
between numerical and standard ordering of numeric types.

number_merge(A, B, M) is equivalent to merge(0, $=<, A, B, M).

### Modes and Determinism

- number_merge(+, +, -) is det

### Exceptions

*(4) instantiation fault *
- List1 or List2 is not ground.
*(5) type error *
- List1 or List2 contains non-numeric elements.

## Examples

Success:
number_merge([2,4,6],[1,3,5],L).
(gives L=[1,2,3,4,5,6]).
number_merge([f(1),f(7)],[f(8),f(10)],L).
(gives L=[f(1),f(7),f(8),f(10)]).
number_merge([f(5),f(8)],[f(1),f(2),f(2),f(5),f(8)],L).
(gives L=[f(1),f(2),f(2),f(5),f(5),f(8),f(8)]).
number_merge([a,w],[a,b,b,r,w],L).
(gives L=[a,a,b,b,r,w,w]).
number_merge([f(2),f(1)],[f(3),f(8)],L).
(gives L=[f(2),f(1),f(3),f(8)]).
Fail:
number_merge([2,4,6],[1,3,5],[1,2,3,4,5]).

## See Also

merge / 3, merge / 5