Swap in Sympy instead of numexpr for more expressive LLMMath tool

libs/langchain/langchain/chains/llm_math/base.py

@@ -1,13 +1,12 @@
 """Chain that interprets a prompt and executes python code to do math."""
 from __future__ import annotations
 
-import math
 import re
 import warnings
 from typing import Any, Dict, List, Optional
 
-import numexpr
 from pydantic import Extra, root_validator
+from sympy import sympify
 
 from langchain.callbacks.manager import (
     AsyncCallbackManagerForChainRun,
@@ -21,7 +20,7 @@
 
 
 class LLMMathChain(Chain):
-    """Chain that interprets a prompt and executes python code to do math.
+    """Chain that interprets a prompt and uses the sympy python package to do math.
 
     Example:
         .. code-block:: python
@@ -75,14 +74,7 @@ def output_keys(self) -> List[str]:
 
     def _evaluate_expression(self, expression: str) -> str:
         try:
-            local_dict = {"pi": math.pi, "e": math.e}
-            output = str(
-                numexpr.evaluate(
-                    expression.strip(),
-                    global_dict={},  # restrict access to globals
-                    local_dict=local_dict,  # add common mathematical functions
-                )
-            )
+            output = str(sympify(expression.strip()))
         except Exception as e:
             raise ValueError(
                 f'LLMMathChain._evaluate("{expression}") raised error: {e}.'

libs/langchain/langchain/chains/llm_math/prompt.py

@@ -1,13 +1,15 @@
 # flake8: noqa
 from langchain.prompts.prompt import PromptTemplate
 
-_PROMPT_TEMPLATE = """Translate a math problem into a expression that can be executed using Python's numexpr library. Use the output of running this code to answer the question.
+_PROMPT_TEMPLATE = """Translate a math problem into a expression that can be executed using the sympify function from the Python package Sympy.
+Use the output of running this code to answer the question.
+Sympify can handle most elementary mathematical expressions, including rounding, factorials, and calculus. It cannot handle string manipulation.
 
 Question: ${{Question with math problem.}}
 ```text
 ${{single line mathematical expression that solves the problem}}
 ```
-...numexpr.evaluate(text)...
+...sympify(text)...
 ```output
 ${{Output of running the code}}
 ```
@@ -19,7 +21,7 @@
 ```text
 37593 * 67
 ```
-...numexpr.evaluate("37593 * 67")...
+...sympify("37593 * 67")...
 ```output
 2518731
 ```
@@ -29,7 +31,7 @@
 ```text
 37593**(1/5)
 ```
-...numexpr.evaluate("37593**(1/5)")...
+...sympify("37593**(1/5)")...
 ```output
 8.222831614237718
 ```