/* Math module -- standard C math library functions, pi and e */

#include "Python.h"

#ifndef _MSC_VER
#ifndef __STDC__
extern double fmod (double, double);
extern double frexp (double, int *);
extern double ldexp (double, int);
extern double modf (double, double *);
#endif /* __STDC__ */
#endif /* _MSC_VER */


#ifdef i860
/* Cray APP has bogus definition of HUGE_VAL in <math.h> */
#undef HUGE_VAL
#endif

#ifdef HUGE_VAL
#define CHECK(x) if (errno != 0) ; \
	else if (-HUGE_VAL <= (x) && (x) <= HUGE_VAL) ; \
	else errno = ERANGE
#else
#define CHECK(x) /* Don't know how to check */
#endif

static PyObject *
math_error(void)
{
	if (errno == EDOM)
		PyErr_SetString(PyExc_ValueError, "math domain error");
	else if (errno == ERANGE)
		PyErr_SetString(PyExc_OverflowError, "math range error");
	else
                /* Unexpected math error */
		PyErr_SetFromErrno(PyExc_ValueError);
	return NULL;
}

static PyObject *
math_1(PyObject *args, double (*func) (double), char *argsfmt)
{
	double x;
	if (!  PyArg_ParseTuple(args, argsfmt, &x))
		return NULL;
	errno = 0;
	PyFPE_START_PROTECT("in math_1", return 0)
	x = (*func)(x);
	PyFPE_END_PROTECT(x)
	CHECK(x);
	if (errno != 0)
		return math_error();
	else
		return PyFloat_FromDouble(x);
}

static PyObject *
math_2(PyObject *args, double (*func) (double, double), char *argsfmt)
{
	double x, y;
	if (! PyArg_ParseTuple(args, argsfmt, &x, &y))
		return NULL;
	errno = 0;
	PyFPE_START_PROTECT("in math_2", return 0)
	x = (*func)(x, y);
	PyFPE_END_PROTECT(x)
	CHECK(x);
	if (errno != 0)
		return math_error();
	else
		return PyFloat_FromDouble(x);
}

#define FUNC1(funcname, func, docstring) \
	static PyObject * math_##funcname(PyObject *self, PyObject *args) { \
		return math_1(args, func, "d:" #funcname); \
	}\
        static char math_##funcname##_doc [] = docstring;

#define FUNC2(funcname, func, docstring) \
	static PyObject * math_##funcname(PyObject *self, PyObject *args) { \
		return math_2(args, func, "dd:" #funcname); \
	}\
        static char math_##funcname##_doc [] = docstring;

FUNC1(acos, acos,
      "acos(x)\n\nReturn the arc cosine of x.")
FUNC1(asin, asin,
      "asin(x)\n\nReturn the arc sine of x.")
FUNC1(atan, atan,
      "atan(x)\n\nReturn the arc tangent of x.")
FUNC2(atan2, atan2,
      "atan2(y, x)\n\nReturn atan(y/x).")
FUNC1(ceil, ceil,
      "ceil(x)\n\nReturn the ceiling of x as a real.")
FUNC1(cos, cos,
      "cos(x)\n\nReturn the cosine of x.")
FUNC1(cosh, cosh,
      "cosh(x)\n\nReturn the hyperbolic cosine of x.")
FUNC1(exp, exp,
      "exp(x)\n\nReturn e raised to the power of x.")
FUNC1(fabs, fabs,
      "fabs(x)\n\nReturn the absolute value of the real x.")
FUNC1(floor, floor,
      "floor(x)\n\nReturn the floor of x as a real.")
     FUNC2(fmod, fmod,
      "fmod(x,y)\n\nReturn x % y.")
FUNC2(hypot, hypot,
      "hypot(x,y)\n\nReturn the Euclidean distance, sqrt(x*x + y*y).")
FUNC1(log, log,
      "log(x)\n\nReturn the natural logarithm of x.")
FUNC1(log10, log10,
      "log10(x)\n\nReturn the base-10 logarithm of x.")
#ifdef MPW_3_1 /* This hack is needed for MPW 3.1 but not for 3.2 ... */
FUNC2(pow, power,
      "pow(x,y)\n\nReturn x**y.")
#else
FUNC2(pow, pow,
      "pow(x,y)\n\nReturn x**y.")
#endif
FUNC1(sin, sin,
      "sin(x)\n\nReturn the sine of x.")
FUNC1(sinh, sinh,
      "sinh(x)\n\nReturn the hyperbolic sine of x.")
FUNC1(sqrt, sqrt,
      "sqrt(x)\n\nReturn the square root of x.")
FUNC1(tan, tan,
      "tan(x)\n\nReturn the tangent of x.")
FUNC1(tanh, tanh,
      "tanh(x)\n\nReturn the hyperbolic tangent of x.")


static PyObject *
math_frexp(PyObject *self, PyObject *args)
{
	double x;
	int i;
	if (! PyArg_ParseTuple(args, "d:frexp", &x))
		return NULL;
	errno = 0;
	x = frexp(x, &i);
	CHECK(x);
	if (errno != 0)
		return math_error();
	return Py_BuildValue("(di)", x, i);
}

static char math_frexp_doc [] =
"frexp(x)\n\
\n\
Return the mantissa and exponent of x, as pair (m, e).\n\
m is a float and e is an int, such that x = m * 2.**e.\n\
If x is 0, m and e are both 0.  Else 0.5 <= abs(m) < 1.0.";


static PyObject *
math_ldexp(PyObject *self, PyObject *args)
{
	double x;
	int exp;
	if (! PyArg_ParseTuple(args, "di:ldexp", &x, &exp))
		return NULL;
	errno = 0;
	PyFPE_START_PROTECT("ldexp", return 0)
	x = ldexp(x, exp);
	PyFPE_END_PROTECT(x)
	CHECK(x);
	if (errno != 0)
		return math_error();
	else
		return PyFloat_FromDouble(x);
}

static char math_ldexp_doc [] = 
"ldexp_doc(x, i)\n\
\n\
Return x * (2**i).";


static PyObject *
math_modf(PyObject *self, PyObject *args)
{
	double x, y;
	if (! PyArg_ParseTuple(args, "d:modf", &x))
		return NULL;
	errno = 0;
#ifdef MPW /* MPW C modf expects pointer to extended as second argument */
        {
		extended e;
		x = modf(x, &e);
		y = e;
        }
#else
	x = modf(x, &y);
#endif
	CHECK(x);
	if (errno != 0)
		return math_error();
	return Py_BuildValue("(dd)", x, y);
}

static char math_modf_doc [] =
"modf(x)\n\
\n\
Return the fractional and integer parts of x. Both results carry the sign\n\
of x.  The integer part is returned as a real.";


static PyMethodDef math_methods[] = {
	{"acos",	math_acos,	METH_VARARGS,	math_acos_doc},
	{"asin",	math_asin,	METH_VARARGS,	math_asin_doc},
	{"atan",	math_atan,	METH_VARARGS,	math_atan_doc},
	{"atan2",	math_atan2,	METH_VARARGS,	math_atan2_doc},
	{"ceil",	math_ceil,	METH_VARARGS,	math_ceil_doc},
	{"cos",		math_cos,	METH_VARARGS,	math_cos_doc},
	{"cosh",	math_cosh,	METH_VARARGS,	math_cosh_doc},
	{"exp",		math_exp,	METH_VARARGS,	math_exp_doc},
	{"fabs",	math_fabs,	METH_VARARGS,	math_fabs_doc},
	{"floor",	math_floor,	METH_VARARGS,	math_floor_doc},
	{"fmod",	math_fmod,	METH_VARARGS,	math_fmod_doc},
	{"frexp",	math_frexp,	METH_VARARGS,	math_frexp_doc},
	{"hypot",	math_hypot,	METH_VARARGS,	math_hypot_doc},
	{"ldexp",	math_ldexp,	METH_VARARGS,	math_ldexp_doc},
	{"log",		math_log,	METH_VARARGS,	math_log_doc},
	{"log10",	math_log10,	METH_VARARGS,	math_log10_doc},
	{"modf",	math_modf,	METH_VARARGS,	math_modf_doc},
	{"pow",		math_pow,	METH_VARARGS,	math_pow_doc},
	{"sin",		math_sin,	METH_VARARGS,	math_sin_doc},
	{"sinh",	math_sinh,	METH_VARARGS,	math_sinh_doc},
	{"sqrt",	math_sqrt,	METH_VARARGS,	math_sqrt_doc},
	{"tan",		math_tan,	METH_VARARGS,	math_tan_doc},
	{"tanh",	math_tanh,	METH_VARARGS,	math_tanh_doc},
	{NULL,		NULL}		/* sentinel */
};


static char module_doc [] =
"This module is always available.  It provides access to the\n\
mathematical functions defined by the C standard.";

DL_EXPORT(void)
initmath(void)
{
	PyObject *m, *d, *v;
	
	m = Py_InitModule3("math", math_methods, module_doc);
	d = PyModule_GetDict(m);

        if (!(v = PyFloat_FromDouble(atan(1.0) * 4.0)))
                goto finally;
	if (PyDict_SetItemString(d, "pi", v) < 0)
                goto finally;
	Py_DECREF(v);

        if (!(v = PyFloat_FromDouble(exp(1.0))))
                goto finally;
	if (PyDict_SetItemString(d, "e", v) < 0)
                goto finally;
	Py_DECREF(v);

  finally:
	return;
}