Index: sasmodels/models/lib/j0_cephes.c
===================================================================
--- sasmodels/models/lib/j0_cephes.c	(revision 0b05c24b7a6d505d30f1aa9ed2c9bca8760d9946)
+++ 	(revision )
@@ -1,253 +1,0 @@
-/*							j0.c
- *
- *	Bessel function of order zero
- *
- *
- *
- * SYNOPSIS:
- *
- * double x, y, j0();
- *
- * y = j0( x );
- *
- *
- *
- * DESCRIPTION:
- *
- * Returns Bessel function of order zero of the argument.
- *
- * The domain is divided into the intervals [0, 5] and
- * (5, infinity). In the first interval the following rational
- * approximation is used:
- *
- *
- *        2         2
- * (w - r  ) (w - r  ) P (w) / Q (w)
- *       1         2    3       8
- *
- *            2
- * where w = x  and the two r's are zeros of the function.
- *
- * In the second interval, the Hankel asymptotic expansion
- * is employed with two rational functions of degree 6/6
- * and 7/7.
- *
- *
- *
- * ACCURACY:
- *
- *                      Absolute error:
- * arithmetic   domain     # trials      peak         rms
- *    DEC       0, 30       10000       4.4e-17     6.3e-18
- *    IEEE      0, 30       60000       4.2e-16     1.1e-16
- *
- */
-
-
-/*
-Cephes Math Library Release 2.8:  June, 2000
-Copyright 1984, 1987, 1989, 2000 by Stephen L. Moshier
-*/
-
-/* Note: all coefficients satisfy the relative error criterion
- * except YP, YQ which are designed for absolute error. */
-
-
- constant double PPJ0[8] = {
-        7.96936729297347051624E-4,
-        8.28352392107440799803E-2,
-        1.23953371646414299388E0,
-        5.44725003058768775090E0,
-        8.74716500199817011941E0,
-        5.30324038235394892183E0,
-        9.99999999999999997821E-1,
-        0.0
-    };
-
- constant double PQJ0[8] = {
-        9.24408810558863637013E-4,
-        8.56288474354474431428E-2,
-        1.25352743901058953537E0,
-        5.47097740330417105182E0,
-        8.76190883237069594232E0,
-        5.30605288235394617618E0,
-        1.00000000000000000218E0,
-        0.0
-    };
-
- constant double QPJ0[8] = {
-        -1.13663838898469149931E-2,
-        -1.28252718670509318512E0,
-        -1.95539544257735972385E1,
-        -9.32060152123768231369E1,
-        -1.77681167980488050595E2,
-        -1.47077505154951170175E2,
-        -5.14105326766599330220E1,
-        -6.05014350600728481186E0,
-    };
-
- constant double QQJ0[8] = {
-        /*  1.00000000000000000000E0,*/
-        6.43178256118178023184E1,
-        8.56430025976980587198E2,
-        3.88240183605401609683E3,
-        7.24046774195652478189E3,
-        5.93072701187316984827E3,
-        2.06209331660327847417E3,
-        2.42005740240291393179E2,
-    };
-
- constant double YPJ0[8] = {
-        1.55924367855235737965E4,
-        -1.46639295903971606143E7,
-        5.43526477051876500413E9,
-        -9.82136065717911466409E11,
-        8.75906394395366999549E13,
-        -3.46628303384729719441E15,
-        4.42733268572569800351E16,
-        -1.84950800436986690637E16,
- };
-
-
- constant double YQJ0[7] = {
-        /* 1.00000000000000000000E0,*/
-        1.04128353664259848412E3,
-        6.26107330137134956842E5,
-        2.68919633393814121987E8,
-        8.64002487103935000337E10,
-        2.02979612750105546709E13,
-        3.17157752842975028269E15,
-        2.50596256172653059228E17,
-  };
-
- constant double RPJ0[8] = {
-        -4.79443220978201773821E9,
-        1.95617491946556577543E12,
-        -2.49248344360967716204E14,
-        9.70862251047306323952E15,
-        0.0,
-        0.0,
-        0.0,
-        0.0
-  };
-
- constant double RQJ0[8] = {
-        /* 1.00000000000000000000E0,*/
-        4.99563147152651017219E2,
-        1.73785401676374683123E5,
-        4.84409658339962045305E7,
-        1.11855537045356834862E10,
-        2.11277520115489217587E12,
-        3.10518229857422583814E14,
-        3.18121955943204943306E16,
-        1.71086294081043136091E18,
-  };
-
- constant double MOJ0[8] = {
-        -6.838999669318810E-002,
-        1.864949361379502E-001,
-        -2.145007480346739E-001,
-        1.197549369473540E-001,
-        -3.560281861530129E-003,
-        -4.969382655296620E-002,
-        -3.355424622293709E-006,
-        7.978845717621440E-001
-  };
-
- constant double PHJ0[8] = {
-        3.242077816988247E+001,
-        -3.630592630518434E+001,
-        1.756221482109099E+001,
-        -4.974978466280903E+000,
-        1.001973420681837E+000,
-        -1.939906941791308E-001,
-        6.490598792654666E-002,
-        -1.249992184872738E-001
-  };
-
- constant double JPJ0[8] = {
-        -6.068350350393235E-008,
-        6.388945720783375E-006,
-        -3.969646342510940E-004,
-        1.332913422519003E-002,
-        -1.729150680240724E-001,
-        0.0,
-        0.0,
-        0.0
- };
-
-double J0(double x) {
-
-//Cephes single precission
-#if FLOAT_SIZE>4
-    double w, z, p, q, xn;
-
-    //const double TWOOPI = 6.36619772367581343075535E-1;
-    const double SQ2OPI = 7.9788456080286535587989E-1;
-    const double PIO4 = 7.85398163397448309616E-1;
-
-    const double DR1 = 5.78318596294678452118E0;
-    const double DR2 = 3.04712623436620863991E1;
-
-
-    if( x < 0 )
-	    x = -x;
-
-    if( x <= 5.0 ) {
-	    z = x * x;
-	    if( x < 1.0e-5 )
-		    return( 1.0 - z/4.0 );
-
-	    p = (z - DR1) * (z - DR2);
-	    p = p * polevl( z, RPJ0, 3)/p1evl( z, RQJ0, 8 );
-	    return( p );
-	}
-
-    w = 5.0/x;
-    q = 25.0/(x*x);
-    p = polevl( q, PPJ0, 6)/polevl( q, PQJ0, 6 );
-    q = polevl( q, QPJ0, 7)/p1evl( q, QQJ0, 7 );
-    xn = x - PIO4;
-
-    double sn, cn;
-    SINCOS(xn, sn, cn);
-    p = p * cn - w * q * sn;
-
-    return( p * SQ2OPI / sqrt(x) );
-//Cephes single precission
-#else
-    double xx, w, z, p, q, xn;
-
-    //const double YZ1 =  0.43221455686510834878;
-    //const double YZ2 = 22.401876406482861405;
-    //const double YZ3 = 64.130620282338755553;
-    const double DR1 =  5.78318596294678452118;
-    const double PIO4F = 0.7853981633974483096;
-
-    if( x < 0 )
-	    xx = -x;
-    else
-	    xx = x;
-
-    if( x <= 2.0 ) {
-	    z = xx * xx;
-	    if( x < 1.0e-3 )
-		    return( 1.0 - 0.25*z );
-
-	    p = (z-DR1) * polevl( z, JPJ0, 4);
-	    return( p );
-	}
-
-    q = 1.0/x;
-    w = sqrt(q);
-
-    p = w * polevl( q, MOJ0, 7);
-    w = q*q;
-    xn = q * polevl( w, PHJ0, 7) - PIO4F;
-    p = p * cos(xn + xx);
-    return(p);
-#endif
-
-}
-
-
Index: sasmodels/models/lib/j1_cephes.c
===================================================================
--- sasmodels/models/lib/j1_cephes.c	(revision 0b05c24b7a6d505d30f1aa9ed2c9bca8760d9946)
+++ 	(revision )
@@ -1,210 +1,0 @@
-/*							j1.c
- *
- *	Bessel function of order one
- *
- *
- *
- * SYNOPSIS:
- *
- * double x, y, j1();
- *
- * y = j1( x );
- *
- *
- *
- * DESCRIPTION:
- *
- * Returns Bessel function of order one of the argument.
- *
- * The domain is divided into the intervals [0, 8] and
- * (8, infinity). In the first interval a 24 term Chebyshev
- * expansion is used. In the second, the asymptotic
- * trigonometric representation is employed using two
- * rational functions of degree 5/5.
- *
- *
- *
- * ACCURACY:
- *
- *                      Absolute error:
- * arithmetic   domain      # trials      peak         rms
- *    DEC       0, 30       10000       4.0e-17     1.1e-17
- *    IEEE      0, 30       30000       2.6e-16     1.1e-16
- *
- *
- */
-
-/*
-Cephes Math Library Release 2.8:  June, 2000
-Copyright 1984, 1987, 1989, 2000 by Stephen L. Moshier
-*/
-
-constant double RPJ1[8] = {
-    -8.99971225705559398224E8,
-    4.52228297998194034323E11,
-    -7.27494245221818276015E13,
-    3.68295732863852883286E15,
-    0.0,
-    0.0,
-    0.0,
-    0.0 };
-
-constant double RQJ1[8] = {
-    6.20836478118054335476E2,
-    2.56987256757748830383E5,
-    8.35146791431949253037E7,
-    2.21511595479792499675E10,
-    4.74914122079991414898E12,
-    7.84369607876235854894E14,
-    8.95222336184627338078E16,
-    5.32278620332680085395E18
-    };
-
-constant double PPJ1[8] = {
-    7.62125616208173112003E-4,
-    7.31397056940917570436E-2,
-    1.12719608129684925192E0,
-    5.11207951146807644818E0,
-    8.42404590141772420927E0,
-    5.21451598682361504063E0,
-    1.00000000000000000254E0,
-    0.0} ;
-
-
-constant double PQJ1[8] = {
-    5.71323128072548699714E-4,
-    6.88455908754495404082E-2,
-    1.10514232634061696926E0,
-    5.07386386128601488557E0,
-    8.39985554327604159757E0,
-    5.20982848682361821619E0,
-    9.99999999999999997461E-1,
-    0.0 };
-
-constant double QPJ1[8] = {
-    5.10862594750176621635E-2,
-    4.98213872951233449420E0,
-    7.58238284132545283818E1,
-    3.66779609360150777800E2,
-    7.10856304998926107277E2,
-    5.97489612400613639965E2,
-    2.11688757100572135698E2,
-    2.52070205858023719784E1 };
-
-constant double QQJ1[8] = {
-    7.42373277035675149943E1,
-    1.05644886038262816351E3,
-    4.98641058337653607651E3,
-    9.56231892404756170795E3,
-    7.99704160447350683650E3,
-    2.82619278517639096600E3,
-    3.36093607810698293419E2,
-    0.0 };
-
-constant double JPJ1[8] = {
-    -4.878788132172128E-009,
-    6.009061827883699E-007,
-    -4.541343896997497E-005,
-    1.937383947804541E-003,
-    -3.405537384615824E-002,
-    0.0,
-    0.0,
-    0.0
-    };
-
-constant double MO1J1[8] = {
-    6.913942741265801E-002,
-    -2.284801500053359E-001,
-    3.138238455499697E-001,
-    -2.102302420403875E-001,
-    5.435364690523026E-003,
-    1.493389585089498E-001,
-    4.976029650847191E-006,
-    7.978845453073848E-001
-    };
-
-constant double PH1J1[8] = {
-    -4.497014141919556E+001,
-    5.073465654089319E+001,
-    -2.485774108720340E+001,
-    7.222973196770240E+000,
-    -1.544842782180211E+000,
-    3.503787691653334E-001,
-    -1.637986776941202E-001,
-    3.749989509080821E-001
-    };
-
-double J1(double x) {
-
-//Cephes double pression function
-#if FLOAT_SIZE>4
-
-    double w, z, p, q, xn;
-
-    const double Z1 = 1.46819706421238932572E1;
-    const double Z2 = 4.92184563216946036703E1;
-    const double THPIO4 =  2.35619449019234492885;
-    const double SQ2OPI = 0.79788456080286535588;
-
-    w = x;
-    if( x < 0 )
-	    w = -x;
-
-    if( w <= 5.0 )
-	{
-	    z = x * x;
-	    w = polevl( z, RPJ1, 3 ) / p1evl( z, RQJ1, 8 );
-	    w = w * x * (z - Z1) * (z - Z2);
-	    return( w );
-	}
-
-    w = 5.0/x;
-    z = w * w;
-
-    p = polevl( z, PPJ1, 6)/polevl( z, PQJ1, 6 );
-    q = polevl( z, QPJ1, 7)/p1evl( z, QQJ1, 7 );
-
-    xn = x - THPIO4;
-
-    double sn, cn;
-    SINCOS(xn, sn, cn);
-    p = p * cn - w * q * sn;
-
-    return( p * SQ2OPI / sqrt(x) );
-
-
-//Single precission version of cephes
-#else
-    double xx, w, z, p, q, xn;
-
-    const double Z1 = 1.46819706421238932572E1;
-    const double THPIO4F =  2.35619449019234492885;    /* 3*pi/4 */
-
-
-    xx = x;
-    if( xx < 0 )
-	    xx = -x;
-
-    if( xx <= 2.0 )
-	{
-	    z = xx * xx;
-	    p = (z-Z1) * xx * polevl( z, JPJ1, 4 );
-	    return( p );
-	}
-
-    q = 1.0/x;
-    w = sqrt(q);
-
-    p = w * polevl( q, MO1J1, 7);
-    w = q*q;
-    xn = q * polevl( w, PH1J1, 7) - THPIO4F;
-    p = p * cos(xn + xx);
-
-    return(p);
-#endif
-}
-
-//Finally J1c function that equals 2*J1(x)/x
-double J1c(double x) {
-    return (x != 0.0 ) ? 2.0*J1(x)/x : 1.0;
-}
Index: sasmodels/models/lib/jn_cephes.c
===================================================================
--- sasmodels/models/lib/jn_cephes.c	(revision bfef528b72ff0998652ebfa1704aa03b745dc7af)
+++ 	(revision )
@@ -1,152 +1,0 @@
-/*							jn.c
- *
- *	Bessel function of integer order
- *
- *
- *
- * SYNOPSIS:
- *
- * int n;
- * double x, y, jn();
- *
- * y = jn( n, x );
- *
- *
- *
- * DESCRIPTION:
- *
- * Returns Bessel function of order n, where n is a
- * (possibly negative) integer.
- *
- * The ratio of jn(x) to j0(x) is computed by backward
- * recurrence.  First the ratio jn/jn-1 is found by a
- * continued fraction expansion.  Then the recurrence
- * relating successive orders is applied until j0 or j1 is
- * reached.
- *
- * If n = 0 or 1 the routine for j0 or j1 is called
- * directly.
- *
- *
- *
- * ACCURACY:
- *
- *                      Absolute error:
- * arithmetic   range      # trials      peak         rms
- *    DEC       0, 30        5500       6.9e-17     9.3e-18
- *    IEEE      0, 30        5000       4.4e-16     7.9e-17
- *
- *
- * Not suitable for large n or x. Use jv() instead.
- *
- */
-
-
-/*							jn.c
-Cephes Math Library Release 2.8:  June, 2000
-Copyright 1984, 1987, 2000 by Stephen L. Moshier
-*/
-
-double jn( int n, double x );
-
-double jn( int n, double x ) {
-
-    const double MACHEP = 1.11022302462515654042E-16;
-    double pkm2, pkm1, pk, xk, r, ans, xinv;
-    int k, sign;
-
-    if( n < 0 ) {
-	    n = -n;
-	    if( (n & 1) == 0 )	/* -1**n */
-		    sign = 1;
-	    else
-		    sign = -1;
-	}
-    else
-	    sign = 1;
-
-    if( x < 0.0 ) {
-	    if( n & 1 )
-		    sign = -sign;
-	    x = -x;
-	}
-
-    if( n == 0 )
-	    return( sign * j0(x) );
-    if( n == 1 )
-	    return( sign * j1(x) );
-    if( n == 2 )
-	    return( sign * (2.0 * j1(x) / x  -  j0(x)) );
-
-    if( x < MACHEP )
-	    return( 0.0 );
-
-    #if FLOAT_SIZE > 4
-        k = 53;
-    #else
-        k = 24;
-    #endif
-
-    pk = 2 * (n + k);
-    ans = pk;
-    xk = x * x;
-
-    do {
-	    pk -= 2.0;
-	    ans = pk - (xk/ans);
-	} while( --k > 0 );
-
-    /* backward recurrence */
-
-    pk = 1.0;
-
-    #if FLOAT_SIZE > 4
-        ans = x/ans;
-        pkm1 = 1.0/ans;
-
-        k = n-1;
-        r = 2 * k;
-
-        do {
-            pkm2 = (pkm1 * r  -  pk * x) / x;
-	        pk = pkm1;
-	        pkm1 = pkm2;
-	        r -= 2.0;
-	    } while( --k > 0 );
-
-        if( fabs(pk) > fabs(pkm1) )
-	        ans = j1(x)/pk;
-        else
-	        ans = j0(x)/pkm1;
-
-	    return( sign * ans );
-
-    #else
-        xinv = 1.0/x;
-        pkm1 = ans * xinv;
-        k = n-1;
-        r = (float )(2 * k);
-
-        do {
-	        pkm2 = (pkm1 * r  -  pk * x) * xinv;
-	        pk = pkm1;
-	        pkm1 = pkm2;
-	        r -= 2.0;
-	    }
-        while( --k > 0 );
-
-        r = pk;
-        if( r < 0 )
-	        r = -r;
-        ans = pkm1;
-        if( ans < 0 )
-	        ans = -ans;
-
-        if( r > ans )  /* if( fabs(pk) > fabs(pkm1) ) */
-	        ans = sign * j1(x)/pk;
-        else
-	        ans = sign * j0(x)/pkm1;
-        return( ans );
-    #endif
-}
-
Index: sasmodels/models/lib/sas_J0.c
===================================================================
--- sasmodels/models/lib/sas_J0.c	(revision a776125d8ac14178bb0492f33e5caaee0644b8f0)
+++ sasmodels/models/lib/sas_J0.c	(revision a776125d8ac14178bb0492f33e5caaee0644b8f0)
@@ -0,0 +1,253 @@
+/*							j0.c
+ *
+ *	Bessel function of order zero
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * double x, y, j0();
+ *
+ * y = j0( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns Bessel function of order zero of the argument.
+ *
+ * The domain is divided into the intervals [0, 5] and
+ * (5, infinity). In the first interval the following rational
+ * approximation is used:
+ *
+ *
+ *        2         2
+ * (w - r  ) (w - r  ) P (w) / Q (w)
+ *       1         2    3       8
+ *
+ *            2
+ * where w = x  and the two r's are zeros of the function.
+ *
+ * In the second interval, the Hankel asymptotic expansion
+ * is employed with two rational functions of degree 6/6
+ * and 7/7.
+ *
+ *
+ *
+ * ACCURACY:
+ *
+ *                      Absolute error:
+ * arithmetic   domain     # trials      peak         rms
+ *    DEC       0, 30       10000       4.4e-17     6.3e-18
+ *    IEEE      0, 30       60000       4.2e-16     1.1e-16
+ *
+ */
+
+
+/*
+Cephes Math Library Release 2.8:  June, 2000
+Copyright 1984, 1987, 1989, 2000 by Stephen L. Moshier
+*/
+
+/* Note: all coefficients satisfy the relative error criterion
+ * except YP, YQ which are designed for absolute error. */
+
+
+ constant double PPJ0[8] = {
+        7.96936729297347051624E-4,
+        8.28352392107440799803E-2,
+        1.23953371646414299388E0,
+        5.44725003058768775090E0,
+        8.74716500199817011941E0,
+        5.30324038235394892183E0,
+        9.99999999999999997821E-1,
+        0.0
+    };
+
+ constant double PQJ0[8] = {
+        9.24408810558863637013E-4,
+        8.56288474354474431428E-2,
+        1.25352743901058953537E0,
+        5.47097740330417105182E0,
+        8.76190883237069594232E0,
+        5.30605288235394617618E0,
+        1.00000000000000000218E0,
+        0.0
+    };
+
+ constant double QPJ0[8] = {
+        -1.13663838898469149931E-2,
+        -1.28252718670509318512E0,
+        -1.95539544257735972385E1,
+        -9.32060152123768231369E1,
+        -1.77681167980488050595E2,
+        -1.47077505154951170175E2,
+        -5.14105326766599330220E1,
+        -6.05014350600728481186E0,
+    };
+
+ constant double QQJ0[8] = {
+        /*  1.00000000000000000000E0,*/
+        6.43178256118178023184E1,
+        8.56430025976980587198E2,
+        3.88240183605401609683E3,
+        7.24046774195652478189E3,
+        5.93072701187316984827E3,
+        2.06209331660327847417E3,
+        2.42005740240291393179E2,
+    };
+
+ constant double YPJ0[8] = {
+        1.55924367855235737965E4,
+        -1.46639295903971606143E7,
+        5.43526477051876500413E9,
+        -9.82136065717911466409E11,
+        8.75906394395366999549E13,
+        -3.46628303384729719441E15,
+        4.42733268572569800351E16,
+        -1.84950800436986690637E16,
+ };
+
+
+ constant double YQJ0[7] = {
+        /* 1.00000000000000000000E0,*/
+        1.04128353664259848412E3,
+        6.26107330137134956842E5,
+        2.68919633393814121987E8,
+        8.64002487103935000337E10,
+        2.02979612750105546709E13,
+        3.17157752842975028269E15,
+        2.50596256172653059228E17,
+  };
+
+ constant double RPJ0[8] = {
+        -4.79443220978201773821E9,
+        1.95617491946556577543E12,
+        -2.49248344360967716204E14,
+        9.70862251047306323952E15,
+        0.0,
+        0.0,
+        0.0,
+        0.0
+  };
+
+ constant double RQJ0[8] = {
+        /* 1.00000000000000000000E0,*/
+        4.99563147152651017219E2,
+        1.73785401676374683123E5,
+        4.84409658339962045305E7,
+        1.11855537045356834862E10,
+        2.11277520115489217587E12,
+        3.10518229857422583814E14,
+        3.18121955943204943306E16,
+        1.71086294081043136091E18,
+  };
+
+ constant double MOJ0[8] = {
+        -6.838999669318810E-002,
+        1.864949361379502E-001,
+        -2.145007480346739E-001,
+        1.197549369473540E-001,
+        -3.560281861530129E-003,
+        -4.969382655296620E-002,
+        -3.355424622293709E-006,
+        7.978845717621440E-001
+  };
+
+ constant double PHJ0[8] = {
+        3.242077816988247E+001,
+        -3.630592630518434E+001,
+        1.756221482109099E+001,
+        -4.974978466280903E+000,
+        1.001973420681837E+000,
+        -1.939906941791308E-001,
+        6.490598792654666E-002,
+        -1.249992184872738E-001
+  };
+
+ constant double JPJ0[8] = {
+        -6.068350350393235E-008,
+        6.388945720783375E-006,
+        -3.969646342510940E-004,
+        1.332913422519003E-002,
+        -1.729150680240724E-001,
+        0.0,
+        0.0,
+        0.0
+ };
+
+double sas_J0(double x) {
+
+//Cephes single precission
+#if FLOAT_SIZE>4
+    double w, z, p, q, xn;
+
+    //const double TWOOPI = 6.36619772367581343075535E-1;
+    const double SQ2OPI = 7.9788456080286535587989E-1;
+    const double PIO4 = 7.85398163397448309616E-1;
+
+    const double DR1 = 5.78318596294678452118E0;
+    const double DR2 = 3.04712623436620863991E1;
+
+
+    if( x < 0 )
+	    x = -x;
+
+    if( x <= 5.0 ) {
+	    z = x * x;
+	    if( x < 1.0e-5 )
+		    return( 1.0 - z/4.0 );
+
+	    p = (z - DR1) * (z - DR2);
+	    p = p * polevl( z, RPJ0, 3)/p1evl( z, RQJ0, 8 );
+	    return( p );
+	}
+
+    w = 5.0/x;
+    q = 25.0/(x*x);
+    p = polevl( q, PPJ0, 6)/polevl( q, PQJ0, 6 );
+    q = polevl( q, QPJ0, 7)/p1evl( q, QQJ0, 7 );
+    xn = x - PIO4;
+
+    double sn, cn;
+    SINCOS(xn, sn, cn);
+    p = p * cn - w * q * sn;
+
+    return( p * SQ2OPI / sqrt(x) );
+//Cephes single precission
+#else
+    double xx, w, z, p, q, xn;
+
+    //const double YZ1 =  0.43221455686510834878;
+    //const double YZ2 = 22.401876406482861405;
+    //const double YZ3 = 64.130620282338755553;
+    const double DR1 =  5.78318596294678452118;
+    const double PIO4F = 0.7853981633974483096;
+
+    if( x < 0 )
+	    xx = -x;
+    else
+	    xx = x;
+
+    if( x <= 2.0 ) {
+	    z = xx * xx;
+	    if( x < 1.0e-3 )
+		    return( 1.0 - 0.25*z );
+
+	    p = (z-DR1) * polevl( z, JPJ0, 4);
+	    return( p );
+	}
+
+    q = 1.0/x;
+    w = sqrt(q);
+
+    p = w * polevl( q, MOJ0, 7);
+    w = q*q;
+    xn = q * polevl( w, PHJ0, 7) - PIO4F;
+    p = p * cos(xn + xx);
+    return(p);
+#endif
+
+}
+
+
Index: sasmodels/models/lib/sas_J1.c
===================================================================
--- sasmodels/models/lib/sas_J1.c	(revision a776125d8ac14178bb0492f33e5caaee0644b8f0)
+++ sasmodels/models/lib/sas_J1.c	(revision a776125d8ac14178bb0492f33e5caaee0644b8f0)
@@ -0,0 +1,210 @@
+/*							j1.c
+ *
+ *	Bessel function of order one
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * double x, y, j1();
+ *
+ * y = j1( x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns Bessel function of order one of the argument.
+ *
+ * The domain is divided into the intervals [0, 8] and
+ * (8, infinity). In the first interval a 24 term Chebyshev
+ * expansion is used. In the second, the asymptotic
+ * trigonometric representation is employed using two
+ * rational functions of degree 5/5.
+ *
+ *
+ *
+ * ACCURACY:
+ *
+ *                      Absolute error:
+ * arithmetic   domain      # trials      peak         rms
+ *    DEC       0, 30       10000       4.0e-17     1.1e-17
+ *    IEEE      0, 30       30000       2.6e-16     1.1e-16
+ *
+ *
+ */
+
+/*
+Cephes Math Library Release 2.8:  June, 2000
+Copyright 1984, 1987, 1989, 2000 by Stephen L. Moshier
+*/
+
+constant double RPJ1[8] = {
+    -8.99971225705559398224E8,
+    4.52228297998194034323E11,
+    -7.27494245221818276015E13,
+    3.68295732863852883286E15,
+    0.0,
+    0.0,
+    0.0,
+    0.0 };
+
+constant double RQJ1[8] = {
+    6.20836478118054335476E2,
+    2.56987256757748830383E5,
+    8.35146791431949253037E7,
+    2.21511595479792499675E10,
+    4.74914122079991414898E12,
+    7.84369607876235854894E14,
+    8.95222336184627338078E16,
+    5.32278620332680085395E18
+    };
+
+constant double PPJ1[8] = {
+    7.62125616208173112003E-4,
+    7.31397056940917570436E-2,
+    1.12719608129684925192E0,
+    5.11207951146807644818E0,
+    8.42404590141772420927E0,
+    5.21451598682361504063E0,
+    1.00000000000000000254E0,
+    0.0} ;
+
+
+constant double PQJ1[8] = {
+    5.71323128072548699714E-4,
+    6.88455908754495404082E-2,
+    1.10514232634061696926E0,
+    5.07386386128601488557E0,
+    8.39985554327604159757E0,
+    5.20982848682361821619E0,
+    9.99999999999999997461E-1,
+    0.0 };
+
+constant double QPJ1[8] = {
+    5.10862594750176621635E-2,
+    4.98213872951233449420E0,
+    7.58238284132545283818E1,
+    3.66779609360150777800E2,
+    7.10856304998926107277E2,
+    5.97489612400613639965E2,
+    2.11688757100572135698E2,
+    2.52070205858023719784E1 };
+
+constant double QQJ1[8] = {
+    7.42373277035675149943E1,
+    1.05644886038262816351E3,
+    4.98641058337653607651E3,
+    9.56231892404756170795E3,
+    7.99704160447350683650E3,
+    2.82619278517639096600E3,
+    3.36093607810698293419E2,
+    0.0 };
+
+constant double JPJ1[8] = {
+    -4.878788132172128E-009,
+    6.009061827883699E-007,
+    -4.541343896997497E-005,
+    1.937383947804541E-003,
+    -3.405537384615824E-002,
+    0.0,
+    0.0,
+    0.0
+    };
+
+constant double MO1J1[8] = {
+    6.913942741265801E-002,
+    -2.284801500053359E-001,
+    3.138238455499697E-001,
+    -2.102302420403875E-001,
+    5.435364690523026E-003,
+    1.493389585089498E-001,
+    4.976029650847191E-006,
+    7.978845453073848E-001
+    };
+
+constant double PH1J1[8] = {
+    -4.497014141919556E+001,
+    5.073465654089319E+001,
+    -2.485774108720340E+001,
+    7.222973196770240E+000,
+    -1.544842782180211E+000,
+    3.503787691653334E-001,
+    -1.637986776941202E-001,
+    3.749989509080821E-001
+    };
+
+double sas_J1(double x) {
+
+//Cephes double pression function
+#if FLOAT_SIZE>4
+
+    double w, z, p, q, xn;
+
+    const double Z1 = 1.46819706421238932572E1;
+    const double Z2 = 4.92184563216946036703E1;
+    const double THPIO4 =  2.35619449019234492885;
+    const double SQ2OPI = 0.79788456080286535588;
+
+    w = x;
+    if( x < 0 )
+	    w = -x;
+
+    if( w <= 5.0 )
+	{
+	    z = x * x;
+	    w = polevl( z, RPJ1, 3 ) / p1evl( z, RQJ1, 8 );
+	    w = w * x * (z - Z1) * (z - Z2);
+	    return( w );
+	}
+
+    w = 5.0/x;
+    z = w * w;
+
+    p = polevl( z, PPJ1, 6)/polevl( z, PQJ1, 6 );
+    q = polevl( z, QPJ1, 7)/p1evl( z, QQJ1, 7 );
+
+    xn = x - THPIO4;
+
+    double sn, cn;
+    SINCOS(xn, sn, cn);
+    p = p * cn - w * q * sn;
+
+    return( p * SQ2OPI / sqrt(x) );
+
+
+//Single precission version of cephes
+#else
+    double xx, w, z, p, q, xn;
+
+    const double Z1 = 1.46819706421238932572E1;
+    const double THPIO4F =  2.35619449019234492885;    /* 3*pi/4 */
+
+
+    xx = x;
+    if( xx < 0 )
+	    xx = -x;
+
+    if( xx <= 2.0 )
+	{
+	    z = xx * xx;
+	    p = (z-Z1) * xx * polevl( z, JPJ1, 4 );
+	    return( p );
+	}
+
+    q = 1.0/x;
+    w = sqrt(q);
+
+    p = w * polevl( q, MO1J1, 7);
+    w = q*q;
+    xn = q * polevl( w, PH1J1, 7) - THPIO4F;
+    p = p * cos(xn + xx);
+
+    return(p);
+#endif
+}
+
+//Finally J1c function that equals 2*J1(x)/x
+double J1c(double x) {
+    return (x != 0.0 ) ? 2.0*J1(x)/x : 1.0;
+}
Index: sasmodels/models/lib/sas_JN.c
===================================================================
--- sasmodels/models/lib/sas_JN.c	(revision a776125d8ac14178bb0492f33e5caaee0644b8f0)
+++ sasmodels/models/lib/sas_JN.c	(revision a776125d8ac14178bb0492f33e5caaee0644b8f0)
@@ -0,0 +1,152 @@
+/*							jn.c
+ *
+ *	Bessel function of integer order
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * int n;
+ * double x, y, jn();
+ *
+ * y = jn( n, x );
+ *
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Returns Bessel function of order n, where n is a
+ * (possibly negative) integer.
+ *
+ * The ratio of jn(x) to j0(x) is computed by backward
+ * recurrence.  First the ratio jn/jn-1 is found by a
+ * continued fraction expansion.  Then the recurrence
+ * relating successive orders is applied until j0 or j1 is
+ * reached.
+ *
+ * If n = 0 or 1 the routine for j0 or j1 is called
+ * directly.
+ *
+ *
+ *
+ * ACCURACY:
+ *
+ *                      Absolute error:
+ * arithmetic   range      # trials      peak         rms
+ *    DEC       0, 30        5500       6.9e-17     9.3e-18
+ *    IEEE      0, 30        5000       4.4e-16     7.9e-17
+ *
+ *
+ * Not suitable for large n or x. Use jv() instead.
+ *
+ */
+
+
+/*							jn.c
+Cephes Math Library Release 2.8:  June, 2000
+Copyright 1984, 1987, 2000 by Stephen L. Moshier
+*/
+
+double sas_JN( int n, double x );
+
+double sas_JN( int n, double x ) {
+
+    const double MACHEP = 1.11022302462515654042E-16;
+    double pkm2, pkm1, pk, xk, r, ans, xinv;
+    int k, sign;
+
+    if( n < 0 ) {
+	    n = -n;
+	    if( (n & 1) == 0 )	/* -1**n */
+		    sign = 1;
+	    else
+		    sign = -1;
+	}
+    else
+	    sign = 1;
+
+    if( x < 0.0 ) {
+	    if( n & 1 )
+		    sign = -sign;
+	    x = -x;
+	}
+
+    if( n == 0 )
+	    return( sign * sas_J0(x) );
+    if( n == 1 )
+	    return( sign * sas_J1(x) );
+    if( n == 2 )
+	    return( sign * (2.0 * sas_J1(x) / x  -  sas_J0(x)) );
+
+    if( x < MACHEP )
+	    return( 0.0 );
+
+    #if FLOAT_SIZE > 4
+        k = 53;
+    #else
+        k = 24;
+    #endif
+
+    pk = 2 * (n + k);
+    ans = pk;
+    xk = x * x;
+
+    do {
+	    pk -= 2.0;
+	    ans = pk - (xk/ans);
+	} while( --k > 0 );
+
+    /* backward recurrence */
+
+    pk = 1.0;
+
+    #if FLOAT_SIZE > 4
+        ans = x/ans;
+        pkm1 = 1.0/ans;
+
+        k = n-1;
+        r = 2 * k;
+
+        do {
+            pkm2 = (pkm1 * r  -  pk * x) / x;
+	        pk = pkm1;
+	        pkm1 = pkm2;
+	        r -= 2.0;
+	    } while( --k > 0 );
+
+        if( fabs(pk) > fabs(pkm1) )
+	        ans = sas_J1(x)/pk;
+        else
+	        ans = sas_J0(x)/pkm1;
+
+	    return( sign * ans );
+
+    #else
+        xinv = 1.0/x;
+        pkm1 = ans * xinv;
+        k = n-1;
+        r = (float )(2 * k);
+
+        do {
+	        pkm2 = (pkm1 * r  -  pk * x) * xinv;
+	        pk = pkm1;
+	        pkm1 = pkm2;
+	        r -= 2.0;
+	    }
+        while( --k > 0 );
+
+        r = pk;
+        if( r < 0 )
+	        r = -r;
+        ans = pkm1;
+        if( ans < 0 )
+	        ans = -ans;
+
+        if( r > ans )  /* if( fabs(pk) > fabs(pkm1) ) */
+	        ans = sign * sas_J1(x)/pk;
+        else
+	        ans = sign * sas_J0(x)/pkm1;
+        return( ans );
+    #endif
+}
+
