From fe33575e2a5cc4c3b6ab4e133ef86de19a393010 Mon Sep 17 00:00:00 2001
From: Nao Pross <np@0hm.ch>
Date: Sun, 12 May 2024 16:07:22 +0200
Subject: Mark functions as deprecated

---
 polymatrix/polymatrix/index.py                     | 29 +++++++++++++++++++++-
 .../polymatrix/utils/mergemonomialindices.py       |  2 ++
 polymatrix/polymatrix/utils/multiplypolynomial.py  |  2 ++
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/polymatrix/polymatrix/index.py b/polymatrix/polymatrix/index.py
index 2a46625..7fe3620 100644
--- a/polymatrix/polymatrix/index.py
+++ b/polymatrix/polymatrix/index.py
@@ -1,8 +1,10 @@
 from __future__ import annotations
 
+import math
+
 from typing import NamedTuple, Iterable, cast
 from collections import UserDict
-from itertools import dropwhile, combinations_with_replacement
+from itertools import product, dropwhile, combinations_with_replacement
 from functools import reduce
 
 # TODO: remove these types, they are here for backward compatiblity
@@ -72,6 +74,8 @@ class MonomialIndex(tuple[VariableIndex]):
 
         return self.degree < other.degree
 
+    # --- Helper / util static methods ---
+
     @staticmethod
     def empty() -> MonomialIndex:
         """ Get an empty monomial index. """
@@ -194,6 +198,29 @@ class PolyDict(UserDict[MonomialIndex, int | float]):
         # This is an alias for readability
         yield from self.values()
 
+    # --- Helper / util static methods ---
+    
+    @staticmethod
+    def product(left: PolyDict, right: PolyDict) -> PolyDict:
+        """ Compute the product of two polynomials """
+        # product of left and right
+        p = PolyDict.empty()
+
+        for (lm, lv), (rm, rv) in product(left.items(), right.items()):
+            pv = lv + rv
+
+            if math.isclose(pv, 0):
+                continue
+
+            pm = MonomialIndex.product(lm, rm)
+            if pm not in p:
+                p[pm] = pv
+
+            elif not math.isclose(p[pm] + pv, 0):
+                p[pm] += pv
+
+        return p
+
 
 class MatrixIndex(NamedTuple):
     """ Index to represent an entry of a matrix. """
diff --git a/polymatrix/polymatrix/utils/mergemonomialindices.py b/polymatrix/polymatrix/utils/mergemonomialindices.py
index 6680ebd..c84a59c 100644
--- a/polymatrix/polymatrix/utils/mergemonomialindices.py
+++ b/polymatrix/polymatrix/utils/mergemonomialindices.py
@@ -1,9 +1,11 @@
 from polymatrix.polymatrix.index import MonomialIndex
 from polymatrix.polymatrix.utils.sortmonomialindices import sort_monomial_indices
+from polymatrix.utils.deprecation import deprecated
 
 
 # NP: this is a werid case of the product
 # NP: merge is not intutive IMHO, find better name
+@deprecated("Replaced by MonomialIndex.product")
 def merge_monomial_indices(
     monomials: tuple[MonomialIndex, ...],
 ) -> MonomialIndex:
diff --git a/polymatrix/polymatrix/utils/multiplypolynomial.py b/polymatrix/polymatrix/utils/multiplypolynomial.py
index 712b34e..0199b98 100644
--- a/polymatrix/polymatrix/utils/multiplypolynomial.py
+++ b/polymatrix/polymatrix/utils/multiplypolynomial.py
@@ -3,9 +3,11 @@ import math
 
 from polymatrix.polymatrix.utils.mergemonomialindices import merge_monomial_indices
 from polymatrix.polymatrix.index import PolyDict
+from polymatrix.utils.deprecation import deprecated
 
 
 # NP: compute index of product of polynomials
+@deprecated("Replaced by PolyDict.product")
 def multiply_polynomial(
     left: PolyDict,
     right: PolyDict,
-- 
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