Index: sansmodels/src/cephes/ndtr.c
===================================================================
--- sansmodels/src/cephes/ndtr.c	(revision 431c9e09a140ccd7d782bfe0778c2b51d45cc094)
+++ sansmodels/src/cephes/ndtr.c	(revision 431c9e09a140ccd7d782bfe0778c2b51d45cc094)
@@ -0,0 +1,527 @@
+/*							ndtr.c
+ *
+ *	Normal distribution function
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * double x, y, ndtr();
+ *
+ * y = ndtr( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns the area under the Gaussian probability density
+ * function, integrated from minus infinity to x:
+ *
+ *                            x
+ *                             -
+ *                   1        | |          2
+ *    ndtr(x)  = ---------    |    exp( - t /2 ) dt
+ *               sqrt(2pi)  | |
+ *                           -
+ *                          -inf.
+ *
+ *             =  ( 1 + erf(z) ) / 2
+ *             =  erfc(z) / 2
+ *
+ * where z = x/sqrt(2). Computation is via the functions
+ * erf and erfc with care to avoid error amplification in computing exp(-x^2).
+ *
+ *
+ * ACCURACY:
+ *
+ *                      Relative error:
+ * arithmetic   domain     # trials      peak         rms
+ *    IEEE     -13,0        30000       1.3e-15     2.2e-16
+ *
+ *
+ * ERROR MESSAGES:
+ *
+ *   message         condition         value returned
+ * erfc underflow    x > 37.519379347       0.0
+ *
+ */
+
+/*							erf.c
+ *
+ *	Error function
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * double x, y, erf();
+ *
+ * y = erf( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * The integral is
+ *
+ *                           x 
+ *                            -
+ *                 2         | |          2
+ *   erf(x)  =  --------     |    exp( - t  ) dt.
+ *              sqrt(pi)   | |
+ *                          -
+ *                           0
+ *
+ * The magnitude of x is limited to 9.231948545 for DEC
+ * arithmetic; 1 or -1 is returned outside this range.
+ *
+ * For 0 <= |x| < 1, erf(x) = x * P4(x**2)/Q5(x**2); otherwise
+ * erf(x) = 1 - erfc(x).
+ *
+ *
+ *
+ * ACCURACY:
+ *
+ *                      Relative error:
+ * arithmetic   domain     # trials      peak         rms
+ *    DEC       0,1         14000       4.7e-17     1.5e-17
+ *    IEEE      0,1         30000       3.7e-16     1.0e-16
+ *
+ */
+
+/*							erfc.c
+ *
+ *	Complementary error function
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * double x, y, erfc();
+ *
+ * y = erfc( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ *
+ *  1 - erf(x) =
+ *
+ *                           inf. 
+ *                             -
+ *                  2         | |          2
+ *   erfc(x)  =  --------     |    exp( - t  ) dt
+ *               sqrt(pi)   | |
+ *                           -
+ *                            x
+ *
+ *
+ * For small x, erfc(x) = 1 - erf(x); otherwise rational
+ * approximations are computed.
+ *
+ * A special function expx2.c is used to suppress error amplification
+ * in computing exp(-x^2).
+ *
+ *
+ * ACCURACY:
+ *
+ *                      Relative error:
+ * arithmetic   domain     # trials      peak         rms
+ *    IEEE      0,26.6417   30000       1.3e-15     2.2e-16
+ *
+ *
+ * ERROR MESSAGES:
+ *
+ *   message         condition              value returned
+ * erfc underflow    x > 9.231948545 (DEC)       0.0
+ *
+ *
+ */
+
+
+
+/*
+Cephes Math Library Release 2.9:  November, 2000
+Copyright 1984, 1987, 1988, 1992, 2000 by Stephen L. Moshier
+*/
+
+
+#include "mconf.h"
+
+extern double SQRTH;
+extern double MAXLOG;
+
+/* Define this macro to suppress error propagation in exp(x^2)
+   by using the expx2 function.  The tradeoff is that doing so
+   generates two calls to the exponential function instead of one.  */
+#define USE_EXPXSQ 1
+
+#ifdef UNK
+static double P[] = {
+ 2.46196981473530512524E-10,
+ 5.64189564831068821977E-1,
+ 7.46321056442269912687E0,
+ 4.86371970985681366614E1,
+ 1.96520832956077098242E2,
+ 5.26445194995477358631E2,
+ 9.34528527171957607540E2,
+ 1.02755188689515710272E3,
+ 5.57535335369399327526E2
+};
+static double Q[] = {
+/* 1.00000000000000000000E0,*/
+ 1.32281951154744992508E1,
+ 8.67072140885989742329E1,
+ 3.54937778887819891062E2,
+ 9.75708501743205489753E2,
+ 1.82390916687909736289E3,
+ 2.24633760818710981792E3,
+ 1.65666309194161350182E3,
+ 5.57535340817727675546E2
+};
+static double R[] = {
+ 5.64189583547755073984E-1,
+ 1.27536670759978104416E0,
+ 5.01905042251180477414E0,
+ 6.16021097993053585195E0,
+ 7.40974269950448939160E0,
+ 2.97886665372100240670E0
+};
+static double S[] = {
+/* 1.00000000000000000000E0,*/
+ 2.26052863220117276590E0,
+ 9.39603524938001434673E0,
+ 1.20489539808096656605E1,
+ 1.70814450747565897222E1,
+ 9.60896809063285878198E0,
+ 3.36907645100081516050E0
+};
+static double T[] = {
+ 9.60497373987051638749E0,
+ 9.00260197203842689217E1,
+ 2.23200534594684319226E3,
+ 7.00332514112805075473E3,
+ 5.55923013010394962768E4
+};
+static double U[] = {
+/* 1.00000000000000000000E0,*/
+ 3.35617141647503099647E1,
+ 5.21357949780152679795E2,
+ 4.59432382970980127987E3,
+ 2.26290000613890934246E4,
+ 4.92673942608635921086E4
+};
+
+#define UTHRESH 37.519379347
+#endif
+
+#ifdef DEC
+static unsigned short P[] = {
+0030207,0054445,0011173,0021706,
+0040020,0067272,0030661,0122075,
+0040756,0151236,0173053,0067042,
+0041502,0106175,0062555,0151457,
+0042104,0102525,0047401,0003667,
+0042403,0116176,0011446,0075303,
+0042551,0120723,0061641,0123275,
+0042600,0070651,0007264,0134516,
+0042413,0061102,0167507,0176625
+};
+static unsigned short Q[] = {
+/*0040200,0000000,0000000,0000000,*/
+0041123,0123257,0165741,0017142,
+0041655,0065027,0173413,0115450,
+0042261,0074011,0021573,0004150,
+0042563,0166530,0013662,0007200,
+0042743,0176427,0162443,0105214,
+0043014,0062546,0153727,0123772,
+0042717,0012470,0006227,0067424,
+0042413,0061103,0003042,0013254
+};
+static unsigned short R[] = {
+0040020,0067272,0101024,0155421,
+0040243,0037467,0056706,0026462,
+0040640,0116017,0120665,0034315,
+0040705,0020162,0143350,0060137,
+0040755,0016234,0134304,0130157,
+0040476,0122700,0051070,0015473
+};
+static unsigned short S[] = {
+/*0040200,0000000,0000000,0000000,*/
+0040420,0126200,0044276,0070413,
+0041026,0053051,0007302,0063746,
+0041100,0144203,0174051,0061151,
+0041210,0123314,0126343,0177646,
+0041031,0137125,0051431,0033011,
+0040527,0117362,0152661,0066201
+};
+static unsigned short T[] = {
+0041031,0126770,0170672,0166101,
+0041664,0006522,0072360,0031770,
+0043013,0100025,0162641,0126671,
+0043332,0155231,0161627,0076200,
+0044131,0024115,0021020,0117343
+};
+static unsigned short U[] = {
+/*0040200,0000000,0000000,0000000,*/
+0041406,0037461,0177575,0032714,
+0042402,0053350,0123061,0153557,
+0043217,0111227,0032007,0164217,
+0043660,0145000,0004013,0160114,
+0044100,0071544,0167107,0125471
+};
+#define UTHRESH 14.0
+#endif
+
+#ifdef IBMPC
+static unsigned short P[] = {
+0x6479,0xa24f,0xeb24,0x3df0,
+0x3488,0x4636,0x0dd7,0x3fe2,
+0x6dc4,0xdec5,0xda53,0x401d,
+0xba66,0xacad,0x518f,0x4048,
+0x20f7,0xa9e0,0x90aa,0x4068,
+0xcf58,0xc264,0x738f,0x4080,
+0x34d8,0x6c74,0x343a,0x408d,
+0x972a,0x21d6,0x0e35,0x4090,
+0xffb3,0x5de8,0x6c48,0x4081
+};
+static unsigned short Q[] = {
+/*0x0000,0x0000,0x0000,0x3ff0,*/
+0x23cc,0xfd7c,0x74d5,0x402a,
+0x7365,0xfee1,0xad42,0x4055,
+0x610d,0x246f,0x2f01,0x4076,
+0x41d0,0x02f6,0x7dab,0x408e,
+0x7151,0xfca4,0x7fa2,0x409c,
+0xf4ff,0xdafa,0x8cac,0x40a1,
+0xede2,0x0192,0xe2a7,0x4099,
+0x42d6,0x60c4,0x6c48,0x4081
+};
+static unsigned short R[] = {
+0x9b62,0x5042,0x0dd7,0x3fe2,
+0xc5a6,0xebb8,0x67e6,0x3ff4,
+0xa71a,0xf436,0x1381,0x4014,
+0x0c0c,0x58dd,0xa40e,0x4018,
+0x960e,0x9718,0xa393,0x401d,
+0x0367,0x0a47,0xd4b8,0x4007
+};
+static unsigned short S[] = {
+/*0x0000,0x0000,0x0000,0x3ff0,*/
+0xce21,0x0917,0x1590,0x4002,
+0x4cfd,0x21d8,0xcac5,0x4022,
+0x2c4d,0x7f05,0x1910,0x4028,
+0x7ff5,0x959c,0x14d9,0x4031,
+0x26c1,0xaa63,0x37ca,0x4023,
+0x2d90,0x5ab6,0xf3de,0x400a
+};
+static unsigned short T[] = {
+0x5d88,0x1e37,0x35bf,0x4023,
+0x067f,0x4e9e,0x81aa,0x4056,
+0x35b7,0xbcb4,0x7002,0x40a1,
+0xef90,0x3c72,0x5b53,0x40bb,
+0x13dc,0xa442,0x2509,0x40eb
+};
+static unsigned short U[] = {
+/*0x0000,0x0000,0x0000,0x3ff0,*/
+0xa6ba,0x3fef,0xc7e6,0x4040,
+0x3aee,0x14c6,0x4add,0x4080,
+0xfd12,0xe680,0xf252,0x40b1,
+0x7c0a,0x0101,0x1940,0x40d6,
+0xf567,0x9dc8,0x0e6c,0x40e8
+};
+#define UTHRESH 37.519379347
+#endif
+
+#ifdef MIEEE
+static unsigned short P[] = {
+0x3df0,0xeb24,0xa24f,0x6479,
+0x3fe2,0x0dd7,0x4636,0x3488,
+0x401d,0xda53,0xdec5,0x6dc4,
+0x4048,0x518f,0xacad,0xba66,
+0x4068,0x90aa,0xa9e0,0x20f7,
+0x4080,0x738f,0xc264,0xcf58,
+0x408d,0x343a,0x6c74,0x34d8,
+0x4090,0x0e35,0x21d6,0x972a,
+0x4081,0x6c48,0x5de8,0xffb3
+};
+static unsigned short Q[] = {
+0x402a,0x74d5,0xfd7c,0x23cc,
+0x4055,0xad42,0xfee1,0x7365,
+0x4076,0x2f01,0x246f,0x610d,
+0x408e,0x7dab,0x02f6,0x41d0,
+0x409c,0x7fa2,0xfca4,0x7151,
+0x40a1,0x8cac,0xdafa,0xf4ff,
+0x4099,0xe2a7,0x0192,0xede2,
+0x4081,0x6c48,0x60c4,0x42d6
+};
+static unsigned short R[] = {
+0x3fe2,0x0dd7,0x5042,0x9b62,
+0x3ff4,0x67e6,0xebb8,0xc5a6,
+0x4014,0x1381,0xf436,0xa71a,
+0x4018,0xa40e,0x58dd,0x0c0c,
+0x401d,0xa393,0x9718,0x960e,
+0x4007,0xd4b8,0x0a47,0x0367
+};
+static unsigned short S[] = {
+0x4002,0x1590,0x0917,0xce21,
+0x4022,0xcac5,0x21d8,0x4cfd,
+0x4028,0x1910,0x7f05,0x2c4d,
+0x4031,0x14d9,0x959c,0x7ff5,
+0x4023,0x37ca,0xaa63,0x26c1,
+0x400a,0xf3de,0x5ab6,0x2d90
+};
+static unsigned short T[] = {
+0x4023,0x35bf,0x1e37,0x5d88,
+0x4056,0x81aa,0x4e9e,0x067f,
+0x40a1,0x7002,0xbcb4,0x35b7,
+0x40bb,0x5b53,0x3c72,0xef90,
+0x40eb,0x2509,0xa442,0x13dc
+};
+static unsigned short U[] = {
+0x4040,0xc7e6,0x3fef,0xa6ba,
+0x4080,0x4add,0x14c6,0x3aee,
+0x40b1,0xf252,0xe680,0xfd12,
+0x40d6,0x1940,0x0101,0x7c0a,
+0x40e8,0x0e6c,0x9dc8,0xf567
+};
+#define UTHRESH 37.519379347
+#endif
+
+#ifdef ANSIPROT
+extern double polevl ( double, void *, int );
+extern double p1evl ( double, void *, int );
+extern double exp ( double );
+extern double log ( double );
+extern double fabs ( double );
+extern double sqrt ( double );
+extern double expx2 ( double, int );
+double erf ( double );
+double erfc ( double );
+static double erfce ( double );
+#else
+double polevl(), p1evl(), exp(), log(), fabs();
+double erf(), erfc(), expx2(), sqrt();
+static double erfce();
+#endif
+
+double ndtr(a)
+double a;
+{
+double x, y, z;
+
+x = a * SQRTH;
+z = fabs(x);
+
+/* if( z < SQRTH ) */
+if( z < 1.0 )
+	y = 0.5 + 0.5 * erf(x);
+
+else
+	{
+#ifdef USE_EXPXSQ
+	/* See below for erfce. */
+	y = 0.5 * erfce(z);
+	/* Multiply by exp(-x^2 / 2)  */
+	z = expx2(a, -1);
+	y = y * sqrt(z);
+#else
+	y = 0.5 * erfc(z);
+#endif
+	if( x > 0 )
+		y = 1.0 - y;
+	}
+
+return(y);
+}
+
+
+double erfc(a)
+double a;
+{
+double p,q,x,y,z;
+
+
+if( a < 0.0 )
+	x = -a;
+else
+	x = a;
+
+if( x < 1.0 )
+	return( 1.0 - erf(a) );
+
+z = -a * a;
+
+if( z < -MAXLOG )
+	{
+under:
+	mtherr( "erfc", UNDERFLOW );
+	if( a < 0 )
+		return( 2.0 );
+	else
+		return( 0.0 );
+	}
+
+#ifdef USE_EXPXSQ
+/* Compute z = exp(z).  */
+z = expx2(a, -1);
+#else
+z = exp(z);
+#endif
+if( x < 8.0 )
+	{
+	p = polevl( x, P, 8 );
+	q = p1evl( x, Q, 8 );
+	}
+else
+	{
+	p = polevl( x, R, 5 );
+	q = p1evl( x, S, 6 );
+	}
+y = (z * p)/q;
+
+if( a < 0 )
+	y = 2.0 - y;
+
+if( y == 0.0 )
+	goto under;
+
+return(y);
+}
+
+
+/* Exponentially scaled erfc function
+   exp(x^2) erfc(x)
+   valid for x > 1.
+   Use with ndtr and expx2.  */
+static double erfce(x)
+double x;
+{
+double p,q;
+
+if( x < 8.0 )
+	{
+	p = polevl( x, P, 8 );
+	q = p1evl( x, Q, 8 );
+	}
+else
+	{
+	p = polevl( x, R, 5 );
+	q = p1evl( x, S, 6 );
+	}
+return (p/q);
+}
+
+
+
+double erf(x)
+double x;
+{
+double y, z;
+
+if( fabs(x) > 1.0 )
+	return( 1.0 - erfc(x) );
+z = x * x;
+y = x * polevl( z, T, 4 ) / p1evl( z, U, 5 );
+return( y );
+
+}
