-/* @(#)exp.c 4.1 12/25/82 */
-
-/*
- exp returns the exponential function of its
- floating-point argument.
-
- The coefficients are #1069 from Hart and Cheney. (22.35D)
-*/
-
-#include <errno.h>
-#include <math.h>
-
-int errno;
-static double p0 = .2080384346694663001443843411e7;
-static double p1 = .3028697169744036299076048876e5;
-static double p2 = .6061485330061080841615584556e2;
-static double q0 = .6002720360238832528230907598e7;
-static double q1 = .3277251518082914423057964422e6;
-static double q2 = .1749287689093076403844945335e4;
-static double log2e = 1.4426950408889634073599247;
-static double sqrt2 = 1.4142135623730950488016887;
-static double maxf = 10000;
-
-double
-exp(arg)
-double arg;
+/*
+ * Copyright (c) 1985 Regents of the University of California.
+ *
+ * Use and reproduction of this software are granted in accordance with
+ * the terms and conditions specified in the Berkeley Software License
+ * Agreement (in particular, this entails acknowledgement of the programs'
+ * source, and inclusion of this notice) with the additional understanding
+ * that all recipients should regard themselves as participants in an
+ * ongoing research project and hence should feel obligated to report
+ * their experiences (good or bad) with these elementary function codes,
+ * using "sendbug 4bsd-bugs@BERKELEY", to the authors.
+ */
+
+#ifndef lint
+static char sccsid[] = "@(#)exp.c 4.3 (Berkeley) 8/21/85";
+#endif not lint
+
+/* EXP(X)
+ * RETURN THE EXPONENTIAL OF X
+ * DOUBLE PRECISION (IEEE 53 bits, VAX D FORMAT 56 BITS)
+ * CODED IN C BY K.C. NG, 1/19/85;
+ * REVISED BY K.C. NG on 2/6/85, 2/15/85, 3/7/85, 3/24/85, 4/16/85.
+ *
+ * Required system supported functions:
+ * scalb(x,n)
+ * copysign(x,y)
+ * finite(x)
+ *
+ * Kernel function:
+ * exp__E(x,c)
+ *
+ * Method:
+ * 1. Argument Reduction: given the input x, find r and integer k such
+ * that
+ * x = k*ln2 + r, |r| <= 0.5*ln2 .
+ * r will be represented as r := z+c for better accuracy.
+ *
+ * 2. Compute expm1(r)=exp(r)-1 by
+ *
+ * expm1(r=z+c) := z + exp__E(z,r)
+ *
+ * 3. exp(x) = 2^k * ( expm1(r) + 1 ).
+ *
+ * Special cases:
+ * exp(INF) is INF, exp(NaN) is NaN;
+ * exp(-INF)= 0;
+ * for finite argument, only exp(0)=1 is exact.
+ *
+ * Accuracy:
+ * exp(x) returns the exponential of x nearly rounded. In a test run
+ * with 1,156,000 random arguments on a VAX, the maximum observed
+ * error was .768 ulps (units in the last place).
+ *
+ * Constants:
+ * The hexadecimal values are the intended ones for the following constants.
+ * The decimal values may be used, provided that the compiler will convert
+ * from decimal to binary accurately enough to produce the hexadecimal values
+ * shown.
+ */
+
+#ifdef VAX /* VAX D format */
+/* double static */
+/* ln2hi = 6.9314718055829871446E-1 , Hex 2^ 0 * .B17217F7D00000 */
+/* ln2lo = 1.6465949582897081279E-12 , Hex 2^-39 * .E7BCD5E4F1D9CC */
+/* lnhuge = 9.4961163736712506989E1 , Hex 2^ 7 * .BDEC1DA73E9010 */
+/* lntiny = -9.5654310917272452386E1 , Hex 2^ 7 * -.BF4F01D72E33AF */
+/* invln2 = 1.4426950408889634148E0 ; Hex 2^ 1 * .B8AA3B295C17F1 */
+static long ln2hix[] = { 0x72174031, 0x0000f7d0};
+static long ln2lox[] = { 0xbcd52ce7, 0xd9cce4f1};
+static long lnhugex[] = { 0xec1d43bd, 0x9010a73e};
+static long lntinyx[] = { 0x4f01c3bf, 0x33afd72e};
+static long invln2x[] = { 0xaa3b40b8, 0x17f1295c};
+#define ln2hi (*(double*)ln2hix)
+#define ln2lo (*(double*)ln2lox)
+#define lnhuge (*(double*)lnhugex)
+#define lntiny (*(double*)lntinyx)
+#define invln2 (*(double*)invln2x)
+#else /* IEEE double */
+double static
+ln2hi = 6.9314718036912381649E-1 , /*Hex 2^ -1 * 1.62E42FEE00000 */
+ln2lo = 1.9082149292705877000E-10 , /*Hex 2^-33 * 1.A39EF35793C76 */
+lnhuge = 7.1602103751842355450E2 , /*Hex 2^ 9 * 1.6602B15B7ECF2 */
+lntiny = -7.5137154372698068983E2 , /*Hex 2^ 9 * -1.77AF8EBEAE354 */
+invln2 = 1.4426950408889633870E0 ; /*Hex 2^ 0 * 1.71547652B82FE */
+#endif
+
+double exp(x)
+double x;