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-rw-r--r--nuttx/lib/math/lib_exp.c346
1 files changed, 109 insertions, 237 deletions
diff --git a/nuttx/lib/math/lib_exp.c b/nuttx/lib/math/lib_exp.c
index a70cb10e7..5b54dbaac 100644
--- a/nuttx/lib/math/lib_exp.c
+++ b/nuttx/lib/math/lib_exp.c
@@ -1,4 +1,14 @@
-/*
+/************************************************************************
+ * lib/math/lib_exp.c
+ *
+ * This file is a part of NuttX:
+ *
+ * Copyright (C) 2012 Gregory Nutt. All rights reserved.
+ * Ported by: Darcy Gong
+ *
+ * It derives from the Rhombs OS math library by Nick Johnson which has
+ * a compatibile, MIT-style license:
+ *
* Copyright (C) 2009-2011 Nick Johnson <nickbjohnson4224 at gmail.com>
*
* Permission to use, copy, modify, and distribute this software for any
@@ -12,242 +22,104 @@
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-
-#include <apps/math.h>
-#include <float.h>
-#include <stdint.h>
-#include <stdbool.h>
-#include <unistd.h>
-
-#define M_E2 (M_E * M_E)
-#define M_E4 (M_E2 * M_E2)
-#define M_E8 (M_E4 * M_E4)
-#define M_E16 (M_E8 * M_E8)
-#define M_E32 (M_E16 * M_E16)
-#define M_E64 (M_E32 * M_E32)
-#define M_E128 (M_E64 * M_E64)
-#define M_E256 (M_E128 * M_E128)
-#define M_E512 (M_E256 * M_E256)
-#define M_E1024 (M_E512 * M_E512)
-
-static double _expi_square_tbl[11] = {
- M_E, // e^1
- M_E2, // e^2
- M_E4, // e^4
- M_E8, // e^8
- M_E16, // e^16
- M_E32, // e^32
- M_E64, // e^64
- M_E128, // e^128
- M_E256, // e^256
- M_E512, // e^512
- M_E1024, // e^1024
+ *
+ ************************************************************************/
+
+/************************************************************************
+ * Included Files
+ ************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/compiler.h>
+
+#include <math.h>
+
+#include "lib_internal.h"
+
+#if CONFIG_HAVE_DOUBLE
+
+/************************************************************************
+ * Private Data
+ ************************************************************************/
+
+static double _dbl_inv_fact[] =
+{
+ 1.0 / 1.0, // 1 / 0!
+ 1.0 / 1.0, // 1 / 1!
+ 1.0 / 2.0, // 1 / 2!
+ 1.0 / 6.0, // 1 / 3!
+ 1.0 / 24.0, // 1 / 4!
+ 1.0 / 120.0, // 1 / 5!
+ 1.0 / 720.0, // 1 / 6!
+ 1.0 / 5040.0, // 1 / 7!
+ 1.0 / 40320.0, // 1 / 8!
+ 1.0 / 362880.0, // 1 / 9!
+ 1.0 / 3628800.0, // 1 / 10!
+ 1.0 / 39916800.0, // 1 / 11!
+ 1.0 / 479001600.0, // 1 / 12!
+ 1.0 / 6227020800.0, // 1 / 13!
+ 1.0 / 87178291200.0, // 1 / 14!
+ 1.0 / 1307674368000.0, // 1 / 15!
+ 1.0 / 20922789888000.0, // 1 / 16!
+ 1.0 / 355687428096000.0, // 1 / 17!
+ 1.0 / 6402373705728000.0, // 1 / 18!
};
-static double _expi(size_t n) {
- size_t i;
- double val;
-
- if (n > 1024) {
- return INFINITY;
- }
-
- val = 1.0;
-
- for (i = 0; n; i++) {
- if (n & (1 << i)) {
- n &= ~(1 << i);
- val *= _expi_square_tbl[i];
- }
- }
-
- return val;
-}
-
-static float _flt_inv_fact[] = {
- 1.0 / 1.0, // 1/0!
- 1.0 / 1.0, // 1/1!
- 1.0 / 2.0, // 1/2!
- 1.0 / 6.0, // 1/3!
- 1.0 / 24.0, // 1/4!
- 1.0 / 120.0, // 1/5!
- 1.0 / 720.0, // 1/6!
- 1.0 / 5040.0, // 1/7!
- 1.0 / 40320.0, // 1/8!
- 1.0 / 362880.0, // 1/9!
- 1.0 / 3628800.0, // 1/10!
-};
-
-float expf(float x) {
- size_t int_part;
- bool invert;
- float value;
- float x0;
- size_t i;
-
- if (x == 0) {
- return 1;
- }
- else if (x < 0) {
- invert = true;
- x = -x;
- }
- else {
- invert = false;
- }
-
- /* extract integer component */
- int_part = (size_t) x;
-
- /* set x to fractional component */
- x -= (float) int_part;
-
- /* perform Taylor series approximation with eleven terms */
- value = 0.0;
- x0 = 1.0;
- for (i = 0; i < 10; i++) {
- value += x0 * _flt_inv_fact[i];
- x0 *= x;
- }
-
- /* multiply by exp of the integer component */
- value *= _expi(int_part);
-
- if (invert) {
- return (1.0 / value);
- }
- else {
- return value;
- }
-}
-
-static double _dbl_inv_fact[] = {
- 1.0 / 1.0, // 1 / 0!
- 1.0 / 1.0, // 1 / 1!
- 1.0 / 2.0, // 1 / 2!
- 1.0 / 6.0, // 1 / 3!
- 1.0 / 24.0, // 1 / 4!
- 1.0 / 120.0, // 1 / 5!
- 1.0 / 720.0, // 1 / 6!
- 1.0 / 5040.0, // 1 / 7!
- 1.0 / 40320.0, // 1 / 8!
- 1.0 / 362880.0, // 1 / 9!
- 1.0 / 3628800.0, // 1 / 10!
- 1.0 / 39916800.0, // 1 / 11!
- 1.0 / 479001600.0, // 1 / 12!
- 1.0 / 6227020800.0, // 1 / 13!
- 1.0 / 87178291200.0, // 1 / 14!
- 1.0 / 1307674368000.0, // 1 / 15!
- 1.0 / 20922789888000.0, // 1 / 16!
- 1.0 / 355687428096000.0, // 1 / 17!
- 1.0 / 6402373705728000.0, // 1 / 18!
-};
-
-double exp(double x) {
- size_t int_part;
- bool invert;
- double value;
- double x0;
- size_t i;
-
- if (x == 0) {
- return 1;
- }
- else if (x < 0) {
- invert = true;
- x = -x;
- }
- else {
- invert = false;
- }
-
- /* extract integer component */
- int_part = (size_t) x;
-
- /* set x to fractional component */
- x -= (double) int_part;
-
- /* perform Taylor series approximation with nineteen terms */
- value = 0.0;
- x0 = 1.0;
- for (i = 0; i < 19; i++) {
- value += x0 * _dbl_inv_fact[i];
- x0 *= x;
- }
-
- /* multiply by exp of the integer component */
- value *= _expi(int_part);
-
- if (invert) {
- return (1.0 / value);
- }
- else {
- return value;
- }
-}
-
-static long double _ldbl_inv_fact[] = {
- 1.0 / 1.0, // 1 / 0!
- 1.0 / 1.0, // 1 / 1!
- 1.0 / 2.0, // 1 / 2!
- 1.0 / 6.0, // 1 / 3!
- 1.0 / 24.0, // 1 / 4!
- 1.0 / 120.0, // 1 / 5!
- 1.0 / 720.0, // 1 / 6!
- 1.0 / 5040.0, // 1 / 7!
- 1.0 / 40320.0, // 1 / 8!
- 1.0 / 362880.0, // 1 / 9!
- 1.0 / 3628800.0, // 1 / 10!
- 1.0 / 39916800.0, // 1 / 11!
- 1.0 / 479001600.0, // 1 / 12!
- 1.0 / 6227020800.0, // 1 / 13!
- 1.0 / 87178291200.0, // 1 / 14!
- 1.0 / 1307674368000.0, // 1 / 15!
- 1.0 / 20922789888000.0, // 1 / 16!
- 1.0 / 355687428096000.0, // 1 / 17!
- 1.0 / 6402373705728000.0, // 1 / 18!
-};
-
-long double expl(long double x) {
- size_t int_part;
- bool invert;
- long double value;
- long double x0;
- size_t i;
-
- if (x == 0) {
- return 1;
- }
- else if (x < 0) {
- invert = true;
- x = -x;
- }
- else {
- invert = false;
- }
-
- /* extract integer component */
- int_part = (size_t) x;
-
- /* set x to fractional component */
- x -= (long double) int_part;
-
- /* perform Taylor series approximation with nineteen terms */
- value = 0.0;
- x0 = 1.0;
- for (i = 0; i < 19; i++) {
- value += x0 * _ldbl_inv_fact[i];
- x0 *= x;
- }
-
- /* multiply by exp of the integer component */
- value *= _expi(int_part);
-
- if (invert) {
- return (1.0 / value);
- }
- else {
- return value;
- }
+/************************************************************************
+ * Public Functions
+ ************************************************************************/
+
+double exp(double x)
+{
+ size_t int_part;
+ bool invert;
+ double value;
+ double x0;
+ size_t i;
+
+ if (x == 0)
+ {
+ return 1;
+ }
+ else if (x < 0)
+ {
+ invert = true;
+ x = -x;
+ }
+ else
+ {
+ invert = false;
+ }
+
+ /* Extract integer component */
+
+ int_part = (size_t) x;
+
+ /* Set x to fractional component */
+
+ x -= (double)int_part;
+
+ /* Perform Taylor series approximation with nineteen terms */
+
+ value = 0.0;
+ x0 = 1.0;
+ for (i = 0; i < 19; i++)
+ {
+ value += x0 * _dbl_inv_fact[i];
+ x0 *= x;
+ }
+
+ /* Multiply by exp of the integer component */
+
+ value *= lib_expi(int_part);
+
+ if (invert)
+ {
+ return (1.0 / value);
+ }
+ else
+ {
+ return value;
+ }
}
+#endif
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