#define IN_LIBEXSLT

#include "libexslt/libexslt.h"

#include <libxml/tree.h>

#include <libxml/xpath.h>

#include <libxml/xpathInternals.h>

#include <libxslt/xsltutils.h>

#include <libxslt/xsltInternals.h>

#include <libxslt/extensions.h>

#include <math.h>

#include <stdlib.h>

#include "exslt.h"

/**

 * exsltMathMin:

 * @ns:  a node-set

 *

 * Implements the EXSLT - Math min() function:

 *    number math:min (node-set)

 *

 * Returns the minimum value of the nodes passed as the argument, or

 *         xmlXPathNAN if @ns is NULL or empty or if one of the nodes

 *         turns into NaN.

 */

static double

exsltMathMin (xmlNodeSetPtr ns) {

    double ret, cur;

    int i;

    if ((ns == NULL) || (ns->nodeNr == 0))

  return(xmlXPathNAN);

    ret = xmlXPathCastNodeToNumber(ns->nodeTab[0]);

    if (xmlXPathIsNaN(ret))

  return(xmlXPathNAN);

    for (i = 1; i < ns->nodeNr; i++) {

  cur = xmlXPathCastNodeToNumber(ns->nodeTab[i]);

  if (xmlXPathIsNaN(cur))

      return(xmlXPathNAN);

  if (cur < ret)

      ret = cur;

    }

    return(ret);

}

/**

 * exsltMathMinFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathMin for use by the XPath processor.

 */

static void

exsltMathMinFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    xmlNodeSetPtr ns;

    double ret;

    void *user = NULL;

    if (nargs != 1) {

  xsltGenericError(xsltGenericErrorContext,

       "math:min: invalid number of arguments\n");

  ctxt->error = XPATH_INVALID_ARITY;

  return;

    }

    /* We need to delay the freeing of value->user */

    if ((ctxt->value != NULL) && (ctxt->value->boolval != 0)) {

        user = ctxt->value->user;

  ctxt->value->boolval = 0;

  ctxt->value->user = NULL;

    }

    ns = xmlXPathPopNodeSet(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathMin(ns);

    xmlXPathFreeNodeSet(ns);

    if (user != NULL)

        xmlFreeNodeList((xmlNodePtr)user);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathMax:

 * @ns:  a node-set

 *

 * Implements the EXSLT - Math max() function:

 *    number math:max (node-set)

 *

 * Returns the maximum value of the nodes passed as arguments, or

 *         xmlXPathNAN if @ns is NULL or empty or if one of the nodes

 *         turns into NaN.

 */

static double

exsltMathMax (xmlNodeSetPtr ns) {

    double ret, cur;

    int i;

    if ((ns == NULL) || (ns->nodeNr == 0))

  return(xmlXPathNAN);

    ret = xmlXPathCastNodeToNumber(ns->nodeTab[0]);

    if (xmlXPathIsNaN(ret))

  return(xmlXPathNAN);

    for (i = 1; i < ns->nodeNr; i++) {

  cur = xmlXPathCastNodeToNumber(ns->nodeTab[i]);

  if (xmlXPathIsNaN(cur))

      return(xmlXPathNAN);

  if (cur > ret)

      ret = cur;

    }

    return(ret);

}

/**

 * exsltMathMaxFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathMax for use by the XPath processor.

 */

static void

exsltMathMaxFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    xmlNodeSetPtr ns;

    double ret;

    void *user = NULL;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    /* We need to delay the freeing of value->user */

    if ((ctxt->value != NULL) && (ctxt->value->boolval != 0)) {

  user = ctxt->value->user;

  ctxt->value->boolval = 0;

  ctxt->value->user = 0;

    }

    ns = xmlXPathPopNodeSet(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathMax(ns);

    xmlXPathFreeNodeSet(ns);

    if (user != NULL)

        xmlFreeNodeList((xmlNodePtr)user);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathHighest:

 * @ns:  a node-set

 *

 * Implements the EXSLT - Math highest() function:

 *    node-set math:highest (node-set)

 *

 * Returns the nodes in the node-set whose value is the maximum value

 *         for the node-set.

 */

static xmlNodeSetPtr

exsltMathHighest (xmlNodeSetPtr ns) {

    xmlNodeSetPtr ret = xmlXPathNodeSetCreate(NULL);

    double max, cur;

    int i;

    if ((ns == NULL) || (ns->nodeNr == 0))

  return(ret);

    max = xmlXPathCastNodeToNumber(ns->nodeTab[0]);

    if (xmlXPathIsNaN(max))

  return(ret);

    else

  xmlXPathNodeSetAddUnique(ret, ns->nodeTab[0]);

    for (i = 1; i < ns->nodeNr; i++) {

  cur = xmlXPathCastNodeToNumber(ns->nodeTab[i]);

  if (xmlXPathIsNaN(cur)) {

      xmlXPathEmptyNodeSet(ret);

      return(ret);

  }

  if (cur < max)

      continue;

  if (cur > max) {

      max = cur;

      xmlXPathEmptyNodeSet(ret);

      xmlXPathNodeSetAddUnique(ret, ns->nodeTab[i]);

      continue;

  }

  xmlXPathNodeSetAddUnique(ret, ns->nodeTab[i]);

    }

    return(ret);

}

/**

 * exsltMathHighestFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathHighest for use by the XPath processor

 */

static void

exsltMathHighestFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    xmlNodeSetPtr ns, ret;

    void *user = NULL;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    /* We need to delay the freeing of value->user */

    if ((ctxt->value != NULL) && ctxt->value->boolval != 0) {

        user = ctxt->value->user;

  ctxt->value->boolval = 0;

  ctxt->value->user = NULL;

    }

    ns = xmlXPathPopNodeSet(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathHighest(ns);

    xmlXPathFreeNodeSet(ns);

    if (user != NULL)

        xmlFreeNodeList((xmlNodePtr)user);

    xmlXPathReturnNodeSet(ctxt, ret);

}

/**

 * exsltMathLowest:

 * @ns:  a node-set

 *

 * Implements the EXSLT - Math lowest() function

 *    node-set math:lowest (node-set)

 *

 * Returns the nodes in the node-set whose value is the minimum value

 *         for the node-set.

 */

static xmlNodeSetPtr

exsltMathLowest (xmlNodeSetPtr ns) {

    xmlNodeSetPtr ret = xmlXPathNodeSetCreate(NULL);

    double min, cur;

    int i;

    if ((ns == NULL) || (ns->nodeNr == 0))

  return(ret);

    min = xmlXPathCastNodeToNumber(ns->nodeTab[0]);

    if (xmlXPathIsNaN(min))

  return(ret);

    else

  xmlXPathNodeSetAddUnique(ret, ns->nodeTab[0]);

    for (i = 1; i < ns->nodeNr; i++) {

  cur = xmlXPathCastNodeToNumber(ns->nodeTab[i]);

  if (xmlXPathIsNaN(cur)) {

      xmlXPathEmptyNodeSet(ret);

      return(ret);

  }

        if (cur > min)

      continue;

  if (cur < min) {

      min = cur;

      xmlXPathEmptyNodeSet(ret);

      xmlXPathNodeSetAddUnique(ret, ns->nodeTab[i]);

            continue;

  }

  xmlXPathNodeSetAddUnique(ret, ns->nodeTab[i]);

    }

    return(ret);

}

/**

 * exsltMathLowestFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathLowest for use by the XPath processor

 */

static void

exsltMathLowestFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    xmlNodeSetPtr ns, ret;

    void *user = NULL;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    /* We need to delay the freeing of value->user */

    if ((ctxt->value != NULL) && (ctxt->value->boolval != 0)) {

        user = ctxt->value->user;

  ctxt->value->boolval = 0;

  ctxt->value->user = NULL;

    }

    ns = xmlXPathPopNodeSet(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathLowest(ns);

    xmlXPathFreeNodeSet(ns);

    if (user != NULL)

        xmlFreeNodeList((xmlNodePtr)user);

    xmlXPathReturnNodeSet(ctxt, ret);

}

/* math other functions */

/* constant values */

#define EXSLT_PI        (const xmlChar *) \

      "3.1415926535897932384626433832795028841971693993751"

#define EXSLT_E         (const xmlChar *) \

      "2.71828182845904523536028747135266249775724709369996"

#define EXSLT_SQRRT2    (const xmlChar *) \

      "1.41421356237309504880168872420969807856967187537694"

#define EXSLT_LN2       (const xmlChar *) \

      "0.69314718055994530941723212145817656807550013436025"

#define EXSLT_LN10      (const xmlChar *) \

      "2.30258509299404568402"

#define EXSLT_LOG2E     (const xmlChar *) \

      "1.4426950408889634074"

#define EXSLT_SQRT1_2   (const xmlChar *) \

      "0.70710678118654752440"

/**

 * exsltMathConstant

 * @name: string

 * @precision:  number

 *

 * Implements the EXSLT - Math constant function:

 *     number math:constant(string, number)

 *

 * Returns a number value of the given constant with the given precision or

 * xmlXPathNAN if name is unknown.

 * The constants are PI, E, SQRRT2, LN2, LN10, LOG2E, and SQRT1_2

 */

static double

exsltMathConstant (xmlChar *name, double precision) {

    xmlChar *str;

    double ret;

    if ((name == NULL) || (xmlXPathIsNaN(precision)) || (precision < 1.0)) {

        return xmlXPathNAN;

    }

    if (xmlStrEqual(name, BAD_CAST "PI")) {

        int len = xmlStrlen(EXSLT_PI);

        if (precision <= len)

            len = (int)precision;

        str = xmlStrsub(EXSLT_PI, 0, len);

    } else if (xmlStrEqual(name, BAD_CAST "E")) {

        int len = xmlStrlen(EXSLT_E);

        if (precision <= len)

            len = (int)precision;

        str = xmlStrsub(EXSLT_E, 0, len);

    } else if (xmlStrEqual(name, BAD_CAST "SQRRT2")) {

        int len = xmlStrlen(EXSLT_SQRRT2);

        if (precision <= len)

            len = (int)precision;

        str = xmlStrsub(EXSLT_SQRRT2, 0, len);

    } else if (xmlStrEqual(name, BAD_CAST "LN2")) {

        int len = xmlStrlen(EXSLT_LN2);

        if (precision <= len)

            len = (int)precision;

        str = xmlStrsub(EXSLT_LN2, 0, len);

    } else if (xmlStrEqual(name, BAD_CAST "LN10")) {

        int len = xmlStrlen(EXSLT_LN10);

        if (precision <= len)

            len = (int)precision;

        str = xmlStrsub(EXSLT_LN10, 0, len);

    } else if (xmlStrEqual(name, BAD_CAST "LOG2E")) {

        int len = xmlStrlen(EXSLT_LOG2E);

        if (precision <= len)

            len = (int)precision;

        str = xmlStrsub(EXSLT_LOG2E, 0, len);

    } else if (xmlStrEqual(name, BAD_CAST "SQRT1_2")) {

        int len = xmlStrlen(EXSLT_SQRT1_2);

        if (precision <= len)

            len = (int)precision;

        str = xmlStrsub(EXSLT_SQRT1_2, 0, len);

    } else {

  str = NULL;

    }

    if (str == NULL)

        return xmlXPathNAN;

    ret = xmlXPathCastStringToNumber(str);

    xmlFree(str);

    return ret;

}

/**

 * exsltMathConstantFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathConstant for use by the XPath processor.

 */

static void

exsltMathConstantFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double   ret;

    xmlChar *name;

    if (nargs != 2) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    name = xmlXPathPopString(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathConstant(name, ret);

    if (name != NULL)

  xmlFree(name);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathRandom:

 *

 * Implements the EXSLT - Math random() function:

 *    number math:random ()

 *

 * Returns a random number between 0 and 1 inclusive.

 */

static double

exsltMathRandom (void) {

    double ret;

    int num;

    num = rand();

    ret = (double)num / (double)RAND_MAX;

    return(ret);

}

/**

 * exsltMathRandomFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathRandom for use by the XPath processor.

 */

static void

exsltMathRandomFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret;

    if (nargs != 0) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = exsltMathRandom();

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathAbs:

 * @num:  a double

 *

 * Implements the EXSLT - Math abs() function:

 *    number math:abs (number)

 *

 * Returns the absolute value of the argument, or xmlXPathNAN if @num is Nan.

 */

static double

exsltMathAbs (double num) {

    double ret;

    if (xmlXPathIsNaN(num))

  return(xmlXPathNAN);

    ret = fabs(num);

    return(ret);

}

/**

 * exsltMathAbsFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathAbs for use by the XPath processor.

 */

static void

exsltMathAbsFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathAbs(ret);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathSqrt:

 * @num:  a double

 *

 * Implements the EXSLT - Math sqrt() function:

 *    number math:sqrt (number)

 *

 * Returns the square root of the argument, or xmlXPathNAN if @num is Nan.

 */

static double

exsltMathSqrt (double num) {

    double ret;

    if (xmlXPathIsNaN(num))

  return(xmlXPathNAN);

    ret = sqrt(num);

    return(ret);

}

/**

 * exsltMathSqrtFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathSqrt for use by the XPath processor.

 */

static void

exsltMathSqrtFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathSqrt(ret);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathPower:

 * @base:  a double

 * @power:  a double

 *

 * Implements the EXSLT - Math power() function:

 *    number math:power (number, number)

 *

 * Returns the power base and power arguments, or xmlXPathNAN

 * if either @base or @power is Nan.

 */

static double

exsltMathPower (double base, double power) {

    double ret;

    if ((xmlXPathIsNaN(base) || xmlXPathIsNaN(power)))

  return(xmlXPathNAN);

    ret = pow(base, power);

    return(ret);

}

/**

 * exsltMathPower:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathPower for use by the XPath processor.

 */

static void

exsltMathPowerFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret, base;

    if (nargs != 2) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    /* power */

    base = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathPower(base, ret);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathLog:

 * @num:  a double

 *

 * Implements the EXSLT - Math log() function:

 *    number math:log (number)

 *

 * Returns the natural log of the argument, or xmlXPathNAN if @num is Nan.

 */

static double

exsltMathLog (double num) {

    double ret;

    if (xmlXPathIsNaN(num))

  return(xmlXPathNAN);

    ret = log(num);

    return(ret);

}

/**

 * exsltMathLogFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathLog for use by the XPath processor.

 */

static void

exsltMathLogFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathLog(ret);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathSin:

 * @num:  a double

 *

 * Implements the EXSLT - Math sin() function:

 *    number math:sin (number)

 *

 * Returns the sine of the argument, or xmlXPathNAN if @num is Nan.

 */

static double

exsltMathSin (double num) {

    double ret;

    if (xmlXPathIsNaN(num))

  return(xmlXPathNAN);

    ret = sin(num);

    return(ret);

}

/**

 * exsltMathSinFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathSin for use by the XPath processor.

 */

static void

exsltMathSinFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathSin(ret);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathCos:

 * @num:  a double

 *

 * Implements the EXSLT - Math cos() function:

 *    number math:cos (number)

 *

 * Returns the cosine of the argument, or xmlXPathNAN if @num is Nan.

 */

static double

exsltMathCos (double num) {

    double ret;

    if (xmlXPathIsNaN(num))

  return(xmlXPathNAN);

    ret = cos(num);

    return(ret);

}

/**

 * exsltMathCosFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathCos for use by the XPath processor.

 */

static void

exsltMathCosFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathCos(ret);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathTan:

 * @num:  a double

 *

 * Implements the EXSLT - Math tan() function:

 *    number math:tan (number)

 *

 * Returns the tangent of the argument, or xmlXPathNAN if @num is Nan.

 */

static double

exsltMathTan (double num) {

    double ret;

    if (xmlXPathIsNaN(num))

  return(xmlXPathNAN);

    ret = tan(num);

    return(ret);

}

/**

 * exsltMathTanFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathTan for use by the XPath processor.

 */

static void

exsltMathTanFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathTan(ret);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathAsin:

 * @num:  a double

 *

 * Implements the EXSLT - Math asin() function:

 *    number math:asin (number)

 *

 * Returns the arc sine of the argument, or xmlXPathNAN if @num is Nan.

 */

static double

exsltMathAsin (double num) {

    double ret;

    if (xmlXPathIsNaN(num))

  return(xmlXPathNAN);

    ret = asin(num);

    return(ret);

}

/**

 * exsltMathAsinFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathAsin for use by the XPath processor.

 */

static void

exsltMathAsinFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathAsin(ret);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathAcos:

 * @num:  a double

 *

 * Implements the EXSLT - Math acos() function:

 *    number math:acos (number)

 *

 * Returns the arc cosine of the argument, or xmlXPathNAN if @num is Nan.

 */

static double

exsltMathAcos (double num) {

    double ret;

    if (xmlXPathIsNaN(num))

  return(xmlXPathNAN);

    ret = acos(num);

    return(ret);

}

/**

 * exsltMathAcosFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathAcos for use by the XPath processor.

 */

static void

exsltMathAcosFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathAcos(ret);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathAtan:

 * @num:  a double

 *

 * Implements the EXSLT - Math atan() function:

 *    number math:atan (number)

 *

 * Returns the arc tangent of the argument, or xmlXPathNAN if @num is Nan.

 */

static double

exsltMathAtan (double num) {

    double ret;

    if (xmlXPathIsNaN(num))

  return(xmlXPathNAN);

    ret = atan(num);

    return(ret);

}

/**

 * exsltMathAtanFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathAtan for use by the XPath processor.

 */

static void

exsltMathAtanFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathAtan(ret);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathAtan2:

 * @y:  a double

 * @x:  a double

 *

 * Implements the EXSLT - Math atan2() function:

 *    number math:atan2 (number, number)

 *

 * Returns the arc tangent function of the y/x arguments, or xmlXPathNAN

 * if either @y or @x is Nan.

 */

static double

exsltMathAtan2 (double y, double x) {

    double ret;

    if ((xmlXPathIsNaN(y) || xmlXPathIsNaN(x)))

  return(xmlXPathNAN);

    ret = atan2(y, x);

    return(ret);

}

/**

 * exsltMathAtan2Function:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathAtan2 for use by the XPath processor.

 */

static void

exsltMathAtan2Function (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret, x;

    if (nargs != 2) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    x = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    /* y */

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathAtan2(ret, x);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathExp:

 * @num:  a double

 *

 * Implements the EXSLT - Math exp() function:

 *    number math:exp (number)

 *

 * Returns the exponential function of the argument, or xmlXPathNAN if

 * @num is Nan.

 */

static double

exsltMathExp (double num) {

    double ret;

    if (xmlXPathIsNaN(num))

  return(xmlXPathNAN);

    ret = exp(num);

    return(ret);

}

/**

 * exsltMathExpFunction:

 * @ctxt:  an XPath parser context

 * @nargs:  the number of arguments

 *

 * Wraps #exsltMathExp for use by the XPath processor.

 */

static void

exsltMathExpFunction (xmlXPathParserContextPtr ctxt, int nargs) {

    double ret;

    if (nargs != 1) {

  xmlXPathSetArityError(ctxt);

  return;

    }

    ret = xmlXPathPopNumber(ctxt);

    if (xmlXPathCheckError(ctxt))

  return;

    ret = exsltMathExp(ret);

    xmlXPathReturnNumber(ctxt, ret);

}

/**

 * exsltMathRegister:

 *

 * Registers the EXSLT - Math module

 */

void

exsltMathRegister (void) {

    xsltRegisterExtModuleFunction ((const xmlChar *) "min",

           EXSLT_MATH_NAMESPACE,

           exsltMathMinFunction);

    xsltRegisterExtModuleFunction ((const xmlChar *) "max",

           EXSLT_MATH_NAMESPACE,

           exsltMathMaxFunction);

    xsltRegisterExtModuleFunction ((const xmlChar *) "highest",

           EXSLT_MATH_NAMESPACE,

           exsltMathHighestFunction);

    xsltRegisterExtModuleFunction ((const xmlChar *) "lowest",

           EXSLT_MATH_NAMESPACE,

           exsltMathLowestFunction);

    xsltRegisterExtModuleFunction ((const xmlChar *) "constant",

           EXSLT_MATH_NAMESPACE,

           exsltMathConstantFunction);

    xsltRegisterExtModuleFunction ((const xmlChar *) "random",

           EXSLT_MATH_NAMESPACE,

           exsltMathRandomFunction);

    xsltRegisterExtModuleFunction ((const xmlChar *) "abs",

           EXSLT_MATH_NAMESPACE,

           exsltMathAbsFunction);

    xsltRegisterExtModuleFunction ((const xmlChar *) "sqrt",