Subtract

Status: Stable

documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

Description

x - y or Subtract[x, y] represents x - y; rewritten by the evaluator to Plus[x, Times[-1, y]] so it inherits Plus's flattening and ordering.

Examples (3)

Every input below was run against the current Mathilda build and its output recorded.

Applications (3)

In[1]:= 7 - 3
Out[1]= 4

In[2]:= Subtract[7, 3]
Out[2]= 4

In[3]:= a - b - c
Out[3]= a - b - c

Implementation notes

builtin_subtract is a thin two-argument rewrite: a - b becomes Plus[a, Times[-1, b]]. It does no arithmetic itself — the returned Plus/Times tree is canonicalised and folded by the evaluator's Plus/Times machinery. Non-binary calls return NULL.

Attributes: Listable, NumericFunction, Protected.

References

• Source: src/arithmetic.c
• Specification: docs/spec/builtins/arithmetic.md
• Tests: tests/test_core.c
• Tests: tests/test_packed_list.c

Notes & additional examples

Notes

x - y is rewritten to Plus[x, Times[-1, y]], so subtraction inherits Plus's flattening and canonical ordering rather than existing as a distinct head in the result.