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authorEric Andersen <andersen@codepoet.org>2001-05-10 00:40:28 +0000
committerEric Andersen <andersen@codepoet.org>2001-05-10 00:40:28 +0000
commit1077fa4d772832f77a677ce7fb7c2d513b959e3f (patch)
tree579bee13fb0b58d2800206366ec2caecbb15f3fc /libm/float/sicif.c
parent22358dd7ce7bb49792204b698f01a6f69b9c8e08 (diff)
uClibc now has a math library. muahahahaha!
-Erik
Diffstat (limited to 'libm/float/sicif.c')
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+/* sicif.c
+ *
+ * Sine and cosine integrals
+ *
+ *
+ *
+ * SYNOPSIS:
+ *
+ * float x, Ci, Si;
+ *
+ * sicif( x, &Si, &Ci );
+ *
+ *
+ * DESCRIPTION:
+ *
+ * Evaluates the integrals
+ *
+ * x
+ * -
+ * | cos t - 1
+ * Ci(x) = eul + ln x + | --------- dt,
+ * | t
+ * -
+ * 0
+ * x
+ * -
+ * | sin t
+ * Si(x) = | ----- dt
+ * | t
+ * -
+ * 0
+ *
+ * where eul = 0.57721566490153286061 is Euler's constant.
+ * The integrals are approximated by rational functions.
+ * For x > 8 auxiliary functions f(x) and g(x) are employed
+ * such that
+ *
+ * Ci(x) = f(x) sin(x) - g(x) cos(x)
+ * Si(x) = pi/2 - f(x) cos(x) - g(x) sin(x)
+ *
+ *
+ * ACCURACY:
+ * Test interval = [0,50].
+ * Absolute error, except relative when > 1:
+ * arithmetic function # trials peak rms
+ * IEEE Si 30000 2.1e-7 4.3e-8
+ * IEEE Ci 30000 3.9e-7 2.2e-8
+ */
+
+/*
+Cephes Math Library Release 2.1: January, 1989
+Copyright 1984, 1987, 1989 by Stephen L. Moshier
+Direct inquiries to 30 Frost Street, Cambridge, MA 02140
+*/
+
+#include <math.h>
+
+static float SN[] = {
+-8.39167827910303881427E-11,
+ 4.62591714427012837309E-8,
+-9.75759303843632795789E-6,
+ 9.76945438170435310816E-4,
+-4.13470316229406538752E-2,
+ 1.00000000000000000302E0,
+};
+static float SD[] = {
+ 2.03269266195951942049E-12,
+ 1.27997891179943299903E-9,
+ 4.41827842801218905784E-7,
+ 9.96412122043875552487E-5,
+ 1.42085239326149893930E-2,
+ 9.99999999999999996984E-1,
+};
+
+static float CN[] = {
+ 2.02524002389102268789E-11,
+-1.35249504915790756375E-8,
+ 3.59325051419993077021E-6,
+-4.74007206873407909465E-4,
+ 2.89159652607555242092E-2,
+-1.00000000000000000080E0,
+};
+static float CD[] = {
+ 4.07746040061880559506E-12,
+ 3.06780997581887812692E-9,
+ 1.23210355685883423679E-6,
+ 3.17442024775032769882E-4,
+ 5.10028056236446052392E-2,
+ 4.00000000000000000080E0,
+};
+
+
+static float FN4[] = {
+ 4.23612862892216586994E0,
+ 5.45937717161812843388E0,
+ 1.62083287701538329132E0,
+ 1.67006611831323023771E-1,
+ 6.81020132472518137426E-3,
+ 1.08936580650328664411E-4,
+ 5.48900223421373614008E-7,
+};
+static float FD4[] = {
+/* 1.00000000000000000000E0,*/
+ 8.16496634205391016773E0,
+ 7.30828822505564552187E0,
+ 1.86792257950184183883E0,
+ 1.78792052963149907262E-1,
+ 7.01710668322789753610E-3,
+ 1.10034357153915731354E-4,
+ 5.48900252756255700982E-7,
+};
+
+
+static float FN8[] = {
+ 4.55880873470465315206E-1,
+ 7.13715274100146711374E-1,
+ 1.60300158222319456320E-1,
+ 1.16064229408124407915E-2,
+ 3.49556442447859055605E-4,
+ 4.86215430826454749482E-6,
+ 3.20092790091004902806E-8,
+ 9.41779576128512936592E-11,
+ 9.70507110881952024631E-14,
+};
+static float FD8[] = {
+/* 1.00000000000000000000E0,*/
+ 9.17463611873684053703E-1,
+ 1.78685545332074536321E-1,
+ 1.22253594771971293032E-2,
+ 3.58696481881851580297E-4,
+ 4.92435064317881464393E-6,
+ 3.21956939101046018377E-8,
+ 9.43720590350276732376E-11,
+ 9.70507110881952025725E-14,
+};
+
+static float GN4[] = {
+ 8.71001698973114191777E-2,
+ 6.11379109952219284151E-1,
+ 3.97180296392337498885E-1,
+ 7.48527737628469092119E-2,
+ 5.38868681462177273157E-3,
+ 1.61999794598934024525E-4,
+ 1.97963874140963632189E-6,
+ 7.82579040744090311069E-9,
+};
+static float GD4[] = {
+/* 1.00000000000000000000E0,*/
+ 1.64402202413355338886E0,
+ 6.66296701268987968381E-1,
+ 9.88771761277688796203E-2,
+ 6.22396345441768420760E-3,
+ 1.73221081474177119497E-4,
+ 2.02659182086343991969E-6,
+ 7.82579218933534490868E-9,
+};
+
+static float GN8[] = {
+ 6.97359953443276214934E-1,
+ 3.30410979305632063225E-1,
+ 3.84878767649974295920E-2,
+ 1.71718239052347903558E-3,
+ 3.48941165502279436777E-5,
+ 3.47131167084116673800E-7,
+ 1.70404452782044526189E-9,
+ 3.85945925430276600453E-12,
+ 3.14040098946363334640E-15,
+};
+static float GD8[] = {
+/* 1.00000000000000000000E0,*/
+ 1.68548898811011640017E0,
+ 4.87852258695304967486E-1,
+ 4.67913194259625806320E-2,
+ 1.90284426674399523638E-3,
+ 3.68475504442561108162E-5,
+ 3.57043223443740838771E-7,
+ 1.72693748966316146736E-9,
+ 3.87830166023954706752E-12,
+ 3.14040098946363335242E-15,
+};
+
+#define EUL 0.57721566490153286061
+extern float MAXNUMF, PIO2F, MACHEPF;
+
+
+
+#ifdef ANSIC
+float logf(float), sinf(float), cosf(float);
+float polevlf(float, float *, int);
+float p1evlf(float, float *, int);
+#else
+float logf(), sinf(), cosf(), polevlf(), p1evlf();
+#endif
+
+
+int sicif( float xx, float *si, float *ci )
+{
+float x, z, c, s, f, g;
+int sign;
+
+x = xx;
+if( x < 0.0 )
+ {
+ sign = -1;
+ x = -x;
+ }
+else
+ sign = 0;
+
+
+if( x == 0.0 )
+ {
+ *si = 0.0;
+ *ci = -MAXNUMF;
+ return( 0 );
+ }
+
+
+if( x > 1.0e9 )
+ {
+ *si = PIO2F - cosf(x)/x;
+ *ci = sinf(x)/x;
+ return( 0 );
+ }
+
+
+
+if( x > 4.0 )
+ goto asympt;
+
+z = x * x;
+s = x * polevlf( z, SN, 5 ) / polevlf( z, SD, 5 );
+c = z * polevlf( z, CN, 5 ) / polevlf( z, CD, 5 );
+
+if( sign )
+ s = -s;
+*si = s;
+*ci = EUL + logf(x) + c; /* real part if x < 0 */
+return(0);
+
+
+
+/* The auxiliary functions are:
+ *
+ *
+ * *si = *si - PIO2;
+ * c = cos(x);
+ * s = sin(x);
+ *
+ * t = *ci * s - *si * c;
+ * a = *ci * c + *si * s;
+ *
+ * *si = t;
+ * *ci = -a;
+ */
+
+
+asympt:
+
+s = sinf(x);
+c = cosf(x);
+z = 1.0/(x*x);
+if( x < 8.0 )
+ {
+ f = polevlf( z, FN4, 6 ) / (x * p1evlf( z, FD4, 7 ));
+ g = z * polevlf( z, GN4, 7 ) / p1evlf( z, GD4, 7 );
+ }
+else
+ {
+ f = polevlf( z, FN8, 8 ) / (x * p1evlf( z, FD8, 8 ));
+ g = z * polevlf( z, GN8, 8 ) / p1evlf( z, GD8, 9 );
+ }
+*si = PIO2F - f * c - g * s;
+if( sign )
+ *si = -( *si );
+*ci = f * s - g * c;
+
+return(0);
+}