gh-101410: customize error messages for 1-arg math functions

Lib/test/mathdata/ieee754.txt

@@ -127,31 +127,31 @@ Trigonometric Functions
 >>> sin(INF)
 Traceback (most recent call last):
 ...
-ValueError: math domain error
+ValueError: expected a finite input, got inf
 >>> sin(NINF)
 Traceback (most recent call last):
 ...
-ValueError: math domain error
+ValueError: expected a finite input, got -inf
 >>> sin(NAN)
 nan
 >>> cos(INF)
 Traceback (most recent call last):
 ...
-ValueError: math domain error
+ValueError: expected a finite input, got inf
 >>> cos(NINF)
 Traceback (most recent call last):
 ...
-ValueError: math domain error
+ValueError: expected a finite input, got -inf
 >>> cos(NAN)
 nan
 >>> tan(INF)
 Traceback (most recent call last):
 ...
-ValueError: math domain error
+ValueError: expected a finite input, got inf
 >>> tan(NINF)
 Traceback (most recent call last):
 ...
-ValueError: math domain error
+ValueError: expected a finite input, got -inf
 >>> tan(NAN)
 nan
 
@@ -169,11 +169,11 @@ True
 >>> asin(INF), asin(NINF)
 Traceback (most recent call last):
 ...
-ValueError: math domain error
+ValueError: expected a number in range from -1 up to 1, got inf
 >>> acos(INF), acos(NINF)
 Traceback (most recent call last):
 ...
-ValueError: math domain error
+ValueError: expected a number in range from -1 up to 1, got inf
 >>> equal(atan(INF), PI/2), equal(atan(NINF), -PI/2)
 (True, True)
 

Lib/test/test_math.py

@@ -2533,10 +2533,10 @@ def test_exception_messages(self):
             math.log(x)
         x = -123
         with self.assertRaisesRegex(ValueError,
-                                    f"expected a positive input, got {x}"):
+                                    "expected a positive input"):
             math.log(x)
         with self.assertRaisesRegex(ValueError,
-                                    f"expected a float or nonnegative integer, got {x}"):
+                                    f"expected a noninteger or positive integer, got {x}"):
             math.gamma(x)
         x = 1.0
         with self.assertRaisesRegex(ValueError,

Misc/NEWS.d/next/Library/2025-02-12-16-37-34.gh-issue-101410.0GInct.rst

@@ -0,0 +1 @@
+Added more detailed messages for domain errors in the :mod:`math` module.

Modules/mathmodule.c

@@ -1089,17 +1089,20 @@ math_2(PyObject *const *args, Py_ssize_t nargs,
     }\
     PyDoc_STRVAR(math_##funcname##_doc, docstring);
 
-FUNC1(acos, acos, 0,
+FUNC1D(acos, acos, 0,
       "acos($module, x, /)\n--\n\n"
       "Return the arc cosine (measured in radians) of x.\n\n"
-      "The result is between 0 and pi.")
-FUNC1(acosh, acosh, 0,
+      "The result is between 0 and pi.",
+      "expected a number in range from -1 up to 1, got %s")
+FUNC1D(acosh, acosh, 0,
       "acosh($module, x, /)\n--\n\n"
-      "Return the inverse hyperbolic cosine of x.")
-FUNC1(asin, asin, 0,
+      "Return the inverse hyperbolic cosine of x.",
+      "expected argument value not less than 1, got %s")
+FUNC1D(asin, asin, 0,
       "asin($module, x, /)\n--\n\n"
       "Return the arc sine (measured in radians) of x.\n\n"
-      "The result is between -pi/2 and pi/2.")
+      "The result is between -pi/2 and pi/2.",
+      "expected a number in range from -1 up to 1, got %s")
 FUNC1(asinh, asinh, 0,
       "asinh($module, x, /)\n--\n\n"
       "Return the inverse hyperbolic sine of x.")
@@ -1161,9 +1164,10 @@ FUNC2(copysign, copysign,
        "Return a float with the magnitude (absolute value) of x but the sign of y.\n\n"
       "On platforms that support signed zeros, copysign(1.0, -0.0)\n"
       "returns -1.0.\n")
-FUNC1(cos, cos, 0,
+FUNC1D(cos, cos, 0,
       "cos($module, x, /)\n--\n\n"
-      "Return the cosine of x (measured in radians).")
+      "Return the cosine of x (measured in radians).",
+      "expected a finite input, got %s")
 FUNC1(cosh, cosh, 1,
       "cosh($module, x, /)\n--\n\n"
       "Return the hyperbolic cosine of x.")
@@ -1228,33 +1232,37 @@ math_floor(PyObject *module, PyObject *number)
 FUNC1AD(gamma, m_tgamma,
       "gamma($module, x, /)\n--\n\n"
       "Gamma function at x.",
-      "expected a float or nonnegative integer, got %s")
-FUNC1A(lgamma, m_lgamma,
+      "expected a noninteger or positive integer, got %s")
+FUNC1AD(lgamma, m_lgamma,
       "lgamma($module, x, /)\n--\n\n"
-      "Natural logarithm of absolute value of Gamma function at x.")
-FUNC1(log1p, m_log1p, 0,
+      "Natural logarithm of absolute value of Gamma function at x.",
+      "expected a noninteger or positive integer, got %s")
+FUNC1D(log1p, m_log1p, 0,
       "log1p($module, x, /)\n--\n\n"
       "Return the natural logarithm of 1+x (base e).\n\n"
-      "The result is computed in a way which is accurate for x near zero.")
+      "The result is computed in a way which is accurate for x near zero.",
+      "expected argument value > -1, got %s")
 FUNC2(remainder, m_remainder,
       "remainder($module, x, y, /)\n--\n\n"
       "Difference between x and the closest integer multiple of y.\n\n"
       "Return x - n*y where n*y is the closest integer multiple of y.\n"
       "In the case where x is exactly halfway between two multiples of\n"
       "y, the nearest even value of n is used. The result is always exact.")
-FUNC1(sin, sin, 0,
+FUNC1D(sin, sin, 0,
       "sin($module, x, /)\n--\n\n"
-      "Return the sine of x (measured in radians).")
+      "Return the sine of x (measured in radians).",
+      "expected a finite input, got %s")
 FUNC1(sinh, sinh, 1,
       "sinh($module, x, /)\n--\n\n"
       "Return the hyperbolic sine of x.")
 FUNC1D(sqrt, sqrt, 0,
       "sqrt($module, x, /)\n--\n\n"
       "Return the square root of x.",
       "expected a nonnegative input, got %s")
-FUNC1(tan, tan, 0,
+FUNC1D(tan, tan, 0,
       "tan($module, x, /)\n--\n\n"
-      "Return the tangent of x (measured in radians).")
+      "Return the tangent of x (measured in radians).",
+      "expected a finite input, got %s")
 FUNC1(tanh, tanh, 0,
       "tanh($module, x, /)\n--\n\n"
       "Return the hyperbolic tangent of x.")
@@ -2232,8 +2240,10 @@ loghelper(PyObject* arg, double (*func)(double))
 
         /* Negative or zero inputs give a ValueError. */
         if (!_PyLong_IsPositive((PyLongObject *)arg)) {
-            PyErr_Format(PyExc_ValueError,
-                         "expected a positive input, got %S", arg);
+            /* The input can be an arbitrary large integer, so we
+               don't include it's value in the error message. */
+            PyErr_SetString(PyExc_ValueError,
+                            "expected a positive input");
             return NULL;
         }