py/modmath: Add domain error checking to sqrt, log, log2, log10.

mbuesch · dpgeorge · commit 17298af61ede · 2015-12-12T15:12:54.000Z
These functions will raise 'ValueError: math domain error' on invalid
input.
diff --git a/py/modmath.c b/py/modmath.c
@@ -25,6 +25,7 @@
  */
 
 #include "py/builtin.h"
+#include "py/nlr.h"
 
 #if MICROPY_PY_BUILTINS_FLOAT && MICROPY_PY_MATH
 
@@ -35,7 +36,10 @@
 /// The `math` module provides some basic mathematical funtions for
 /// working with floating-point numbers.
 
-//TODO: Change macros to check for overflow and raise OverflowError or RangeError
+STATIC NORETURN void math_error(void) {
+    nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "math domain error"));
+}
+
 #define MATH_FUN_1(py_name, c_name) \
     STATIC mp_obj_t mp_math_ ## py_name(mp_obj_t x_obj) { return mp_obj_new_float(MICROPY_FLOAT_C_FUN(c_name)(mp_obj_get_float(x_obj))); } \
     STATIC MP_DEFINE_CONST_FUN_OBJ_1(mp_math_## py_name ## _obj, mp_math_ ## py_name);
@@ -52,14 +56,24 @@
     STATIC mp_obj_t mp_math_ ## py_name(mp_obj_t x_obj) { mp_int_t x = MICROPY_FLOAT_C_FUN(c_name)(mp_obj_get_float(x_obj)); return mp_obj_new_int(x); } \
     STATIC MP_DEFINE_CONST_FUN_OBJ_1(mp_math_## py_name ## _obj, mp_math_ ## py_name);
 
+#define MATH_FUN_1_ERRCOND(py_name, c_name, error_condition) \
+    STATIC mp_obj_t mp_math_ ## py_name(mp_obj_t x_obj) { \
+        mp_float_t x = mp_obj_get_float(x_obj); \
+        if (error_condition) { \
+            math_error(); \
+        } \
+        return mp_obj_new_float(MICROPY_FLOAT_C_FUN(c_name)(x)); \
+    } \
+    STATIC MP_DEFINE_CONST_FUN_OBJ_1(mp_math_## py_name ## _obj, mp_math_ ## py_name);
+
 #if MP_NEED_LOG2
 // 1.442695040888963407354163704 is 1/_M_LN2
 #define log2(x) (log(x) * 1.442695040888963407354163704)
 #endif
 
 /// \function sqrt(x)
 /// Returns the square root of `x`.
-MATH_FUN_1(sqrt, sqrt)
+MATH_FUN_1_ERRCOND(sqrt, sqrt, (x < (mp_float_t)0.0))
 /// \function pow(x, y)
 /// Returns `x` to the power of `y`.
 MATH_FUN_2(pow, pow)
@@ -69,9 +83,9 @@ MATH_FUN_1(exp, exp)
 /// \function expm1(x)
 MATH_FUN_1(expm1, expm1)
 /// \function log2(x)
-MATH_FUN_1(log2, log2)
+MATH_FUN_1_ERRCOND(log2, log2, (x <= (mp_float_t)0.0))
 /// \function log10(x)
-MATH_FUN_1(log10, log10)
+MATH_FUN_1_ERRCOND(log10, log10, (x <= (mp_float_t)0.0))
 /// \function cosh(x)
 MATH_FUN_1(cosh, cosh)
 /// \function sinh(x)
@@ -139,11 +153,19 @@ MATH_FUN_1(lgamma, lgamma)
 
 // log(x[, base])
 STATIC mp_obj_t mp_math_log(mp_uint_t n_args, const mp_obj_t *args) {
-    mp_float_t l = MICROPY_FLOAT_C_FUN(log)(mp_obj_get_float(args[0]));
+    mp_float_t x = mp_obj_get_float(args[0]);
+    if (x <= (mp_float_t)0.0) {
+        math_error();
+    }
+    mp_float_t l = MICROPY_FLOAT_C_FUN(log)(x);
     if (n_args == 1) {
         return mp_obj_new_float(l);
     } else {
-        return mp_obj_new_float(l / MICROPY_FLOAT_C_FUN(log)(mp_obj_get_float(args[1])));
+        mp_float_t base = mp_obj_get_float(args[1]);
+        if (base <= (mp_float_t)0.0) {
+            math_error();
+        }
+        return mp_obj_new_float(l / MICROPY_FLOAT_C_FUN(log)(base));
     }
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_math_log_obj, 1, 2, mp_math_log);
diff --git a/tests/float/math_fun.py b/tests/float/math_fun.py
@@ -9,15 +9,14 @@
 
 test_values = [-100., -1.23456, -1, -0.5, 0.0, 0.5, 1.23456, 100.]
 test_values_small = [-10., -1.23456, -1, -0.5, 0.0, 0.5, 1.23456, 10.] # so we don't overflow 32-bit precision
-p_test_values = [0.1, 0.5, 1.23456]
 unit_range_test_values = [-1., -0.75, -0.5, -0.25, 0., 0.25, 0.5, 0.75, 1.]
 
-functions = [('sqrt', sqrt, p_test_values),
+functions = [('sqrt', sqrt, test_values),
              ('exp', exp, test_values_small),
              ('expm1', expm1, test_values_small),
-             ('log', log, p_test_values),
-             ('log2', log2, p_test_values),
-             ('log10', log10, p_test_values),
+             ('log', log, test_values),
+             ('log2', log2, test_values),
+             ('log10', log10, test_values),
              ('cosh', cosh, test_values_small),
              ('sinh', sinh, test_values_small),
              ('tanh', tanh, test_values_small),
@@ -41,7 +40,10 @@
 for function_name, function, test_vals in functions:
     print(function_name)
     for value in test_vals:
-        print("{:.5g}".format(function(value)))
+        try:
+            print("{:.5g}".format(function(value)))
+        except ValueError as e:
+            print(str(e))
 
 tuple_functions = [('frexp', frexp, test_values),
                    ('modf', modf, test_values),
@@ -59,10 +61,13 @@
                     ('atan2', atan2, ((1., 0.), (0., 1.), (2., 0.5), (-3., 5.), (-3., -4.),)),
                     ('fmod', fmod, ((1., 1.), (0., 1.), (2., 0.5), (-3., 5.), (-3., -4.),)),
                     ('ldexp', ldexp, ((1., 0), (0., 1), (2., 2), (3., -2), (-3., -4),)),
-                    ('log', log, ((2., 2.), (3., 2.), (4., 5.))),
+                    ('log', log, ((2., 2.), (3., 2.), (4., 5.), (0., 1.), (1., 0.), (-1., 1.), (1., -1.))),
                    ]
 
 for function_name, function, test_vals in binary_functions:
     print(function_name)
     for value1, value2 in test_vals:
-        print("{:.5g}".format(function(value1, value2)))
+        try:
+            print("{:.5g}".format(function(value1, value2)))
+        except ValueError as e:
+            print(str(e))
