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gon.c
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gon.c
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union dbl_ul {
double dbl;
struct {
#if (__BYTE_ORDER == __BIG_ENDIAN) || defined(__arm__)
u32 ms;
u32 ls;
#else
u32 ls;
u32 ms;
#endif
} ul;
};
#define GET_MSDW(x) ({ union dbl_ul u = { .dbl = (x) }; u.ul.ms; })
#define GET_LSDW(x) ({ union dbl_ul u = { .dbl = (x) }; u.ul.ls; })
#define SET_MSDW(x,y) ({ union dbl_ul u = { .dbl = (x) }; u.ul.ms = (y);u.dbl;})
#define SET_LSDW(x,y) ({ union dbl_ul u = { .dbl = (x) }; u.ul.ls = (y);u.dbl;})
#define DW_TO_DBL(x, y) ({ union dbl_ul u = { .ul = { .ms = x, .ls = y } }; \
u.dbl; });
inline double fabs(double x)
{
return ({ union dbl_ul u = { .dbl = x }; u.ul.ms &= 0x7fffffff;u.dbl;});
}
static inline double copysign(double arg2, double arg1)
{
return SET_MSDW(arg2, (GET_MSDW(arg2) & 0x7fffffff) |
(GET_MSDW(arg1) & 0x80000000));
}
double scalbn(double x, int n)
{
static const double
two54 = 1.80143985094819840000e+16, // 0x43500000, 0x00000000
twom54 = 5.55111512312578270212e-17, // 0x3C900000, 0x00000000
huge = 1.0e+300, tiny = 1.0e-300;
s32 k, hx, lx;
hx = GET_MSDW(x);
lx = GET_LSDW(x);
k = (hx & 0x7ff00000) >> 20; /* extract exponent */
if (k == 0) { /* 0 or subnormal x */
if ((lx | (hx & 0x7fffffff)) == 0)
return x; /* +-0 */
x *= two54;
hx = GET_MSDW(x);
k = ((hx & 0x7ff00000) >> 20) - 54;
if (n < -50000)
return tiny * x; /*underflow */
}
if (k == 0x7ff)
return x + x; /* NaN or Inf */
k = k + n;
if (k > 0x7fe)
return huge * copysign(huge, x); /* overflow */
if (k > 0) /* normal result */
return SET_MSDW(x, (hx & 0x800fffff) | (k << 20));
if (k <= -54) {
if (n > 50000) /* in case integer overflow in n+k */
return huge * copysign(huge, x); /*overflow */
else
return tiny * copysign(tiny, x); /*underflow */
}
k += 54; /* subnormal result */
return SET_MSDW(x, (hx & 0x800fffff) | (k << 20)) * twom54;
}
double floor(double x)
{
static const double huge = 1.0e300;
s32 i0, i1, j0;
u32 i, j;
i0 = GET_MSDW(x);
i1 = GET_LSDW(x);
j0 = ((i0 >> 20) & 0x7ff) - 0x3ff;
if (j0 < 20) {
if (j0 < 0) { /* raise inexact if x != 0 */
if (huge + x > 0.0) { /* return 0*sign(x) if |x|<1 */
if (i0 >= 0)
i0 = i1 = 0;
else if (((i0 & 0x7fffffff) | i1) != 0) {
i0 = 0xbff00000;
i1 = 0;
}
}
} else {
i = (0x000fffff) >> j0;
if (((i0 & i) | i1) == 0)
return x; /* x is integral */
if (huge + x > 0.0) { /* raise inexact flag */
if (i0 < 0)
i0 += (0x00100000) >> j0;
i0 &= (~i);
i1 = 0;
}
}
} else if (j0 > 51) {
if (j0 == 0x400)
return x + x; /* inf or NaN */
else
return x; /* x is integral */
} else {
i = ((u32) (0xffffffff)) >> (j0 - 20);
if ((i1 & i) == 0)
return x; /* x is integral */
if (huge + x > 0.0) { /* raise inexact flag */
if (i0 < 0) {
if (j0 == 20)
i0 += 1;
else {
j = i1 + (1 << (52 - j0));
if (j < i1)
i0 += 1; /* got a carry */
i1 = j;
}
}
i1 &= (~i);
}
}
return DW_TO_DBL(i0, i1);
}
static int __rem_pio2(double *x, double *y, int e0, int nx, int prec,
const s32 * ipio2)
{
static const int init_jk[] = { 2, 3, 4, 6 }; /* initial value for jk */
static const double PIo2[] = {
1.57079625129699707031e+00, /* 0x3FF921FB, 0x40000000 */
7.54978941586159635335e-08, /* 0x3E74442D, 0x00000000 */
5.39030252995776476554e-15, /* 0x3CF84698, 0x80000000 */
3.28200341580791294123e-22, /* 0x3B78CC51, 0x60000000 */
1.27065575308067607349e-29, /* 0x39F01B83, 0x80000000 */
1.22933308981111328932e-36, /* 0x387A2520, 0x40000000 */
2.73370053816464559624e-44, /* 0x36E38222, 0x80000000 */
2.16741683877804819444e-51, /* 0x3569F31D, 0x00000000 */
};
static const double
zero = 0.0,
one = 1.0,
two24 = 1.67772160000000000000e+07, // 0x41700000, 0x00000000
twon24 = 5.96046447753906250000e-08; // 0x3E700000, 0x00000000
s32 jz, jx, jv, jp, jk, carry, n, iq[20], i, j, k, m, q0, ih;
double z, fw, f[20], fq[20], q[20];
/* initialize jk */
jk = init_jk[prec];
jp = jk;
/* determine jx,jv,q0, note that 3>q0 */
jx = nx - 1;
jv = (e0 - 3) / 24;
if (jv < 0)
jv = 0;
q0 = e0 - 24 * (jv + 1);
/* set up f[0] to f[jx+jk] where f[jx+jk] = ipio2[jv+jk] */
j = jv - jx;
m = jx + jk;
for (i = 0; i <= m; i++, j++)
f[i] = (j < 0) ? zero : (double)ipio2[j];
/* compute q[0],q[1],...q[jk] */
for (i = 0; i <= jk; i++) {
for (j = 0, fw = 0.0; j <= jx; j++)
fw += x[j] * f[jx + i - j];
q[i] = fw;
}
jz = jk;
recompute:
/* distill q[] into iq[] reversingly */
for (i = 0, j = jz, z = q[jz]; j > 0; i++, j--) {
fw = (double)((s32) (twon24 * z));
iq[i] = (s32) (z - two24 * fw);
z = q[j - 1] + fw;
}
/* compute n */
z = scalbn(z, q0); /* actual value of z */
z -= 8.0 * floor(z * 0.125); /* trim off integer >= 8 */
n = (s32) z;
z -= (double)n;
ih = 0;
if (q0 > 0) { /* need iq[jz-1] to determine n */
i = (iq[jz - 1] >> (24 - q0));
n += i;
iq[jz - 1] -= i << (24 - q0);
ih = iq[jz - 1] >> (23 - q0);
} else if (q0 == 0)
ih = iq[jz - 1] >> 23;
else if (z >= 0.5)
ih = 2;
if (ih > 0) { /* q > 0.5 */
n += 1;
carry = 0;
for (i = 0; i < jz; i++) { /* compute 1-q */
j = iq[i];
if (carry == 0) {
if (j != 0) {
carry = 1;
iq[i] = 0x1000000 - j;
}
} else
iq[i] = 0xffffff - j;
}
if (q0 > 0) { /* rare case: chance is 1 in 12 */
switch (q0) {
case 1:
iq[jz - 1] &= 0x7fffff;
break;
case 2:
iq[jz - 1] &= 0x3fffff;
break;
}
}
if (ih == 2) {
z = one - z;
if (carry != 0)
z -= scalbn(one, q0);
}
}
/* check if recomputation is needed */
if (z == zero) {
j = 0;
for (i = jz - 1; i >= jk; i--)
j |= iq[i];
if (j == 0) { /* need recomputation */
for (k = 1; iq[jk - k] == 0; k++)
; /* k = no. of terms needed */
/* add q[jz+1] to q[jz+k] */
for (i = jz + 1; i <= jz + k; i++) {
f[jx + i] = (double)ipio2[jv + i];
for (j = 0, fw = 0.0; j <= jx; j++)
fw += x[j] * f[jx + i - j];
q[i] = fw;
}
jz += k;
goto recompute;
}
}
/* chop off zero terms */
if (z == 0.0) {
jz -= 1;
q0 -= 24;
while (iq[jz] == 0) {
jz--;
q0 -= 24;
}
} else { /* break z into 24-bit if necessary */
z = scalbn(z, -q0);
if (z >= two24) {
fw = (double)((s32) (twon24 * z));
iq[jz] = (s32) (z - two24 * fw);
jz += 1;
q0 += 24;
iq[jz] = (s32) fw;
} else
iq[jz] = (s32) z;
}
/* convert integer "bit" chunk to floating-point value */
fw = scalbn(one, q0);
for (i = jz; i >= 0; i--) {
q[i] = fw * (double)iq[i];
fw *= twon24;
}
/* compute PIo2[0,...,jp]*q[jz,...,0] */
for (i = jz; i >= 0; i--) {
for (fw = 0.0, k = 0; k <= jp && k <= jz - i; k++)
fw += PIo2[k] * q[i + k];
fq[jz - i] = fw;
}
/* compress fq[] into y[] */
switch (prec) {
case 0:
fw = 0.0;
for (i = jz; i >= 0; i--)
fw += fq[i];
y[0] = (ih == 0) ? fw : -fw;
break;
case 1:
case 2:
fw = 0.0;
for (i = jz; i >= 0; i--)
fw += fq[i];
y[0] = (ih == 0) ? fw : -fw;
fw = fq[0] - fw;
for (i = 1; i <= jz; i++)
fw += fq[i];
y[1] = (ih == 0) ? fw : -fw;
break;
case 3: /* painful */
for (i = jz; i > 0; i--) {
fw = fq[i - 1] + fq[i];
fq[i] += fq[i - 1] - fw;
fq[i - 1] = fw;
}
for (i = jz; i > 1; i--) {
fw = fq[i - 1] + fq[i];
fq[i] += fq[i - 1] - fw;
fq[i - 1] = fw;
}
for (fw = 0.0, i = jz; i >= 2; i--)
fw += fq[i];
if (ih == 0) {
y[0] = fq[0];
y[1] = fq[1];
y[2] = fw;
} else {
y[0] = -fq[0];
y[1] = -fq[1];
y[2] = -fw;
}
}
return n & 7;
}
s32 rem_pio2(double x, double *y)
{
static const s32 two_over_pi[] = {
0xA2F983, 0x6E4E44, 0x1529FC, 0x2757D1, 0xF534DD, 0xC0DB62,
0x95993C, 0x439041, 0xFE5163, 0xABDEBB, 0xC561B7, 0x246E3A,
0x424DD2, 0xE00649, 0x2EEA09, 0xD1921C, 0xFE1DEB, 0x1CB129,
0xA73EE8, 0x8235F5, 0x2EBB44, 0x84E99C, 0x7026B4, 0x5F7E41,
0x3991D6, 0x398353, 0x39F49C, 0x845F8B, 0xBDF928, 0x3B1FF8,
0x97FFDE, 0x05980F, 0xEF2F11, 0x8B5A0A, 0x6D1F6D, 0x367ECF,
0x27CB09, 0xB74F46, 0x3F669E, 0x5FEA2D, 0x7527BA, 0xC7EBE5,
0xF17B3D, 0x0739F7, 0x8A5292, 0xEA6BFB, 0x5FB11F, 0x8D5D08,
0x560330, 0x46FC7B, 0x6BABF0, 0xCFBC20, 0x9AF436, 0x1DA9E3,
0x91615E, 0xE61B08, 0x659985, 0x5F14A0, 0x68408D, 0xFFD880,
0x4D7327, 0x310606, 0x1556CA, 0x73A8C9, 0x60E27B, 0xC08C6B,
};
static const s32 npio2_hw[] = {
0x3FF921FB, 0x400921FB, 0x4012D97C, 0x401921FB, 0x401F6A7A,
0x4022D97C, 0x4025FDBB, 0x402921FB, 0x402C463A, 0x402F6A7A,
0x4031475C, 0x4032D97C, 0x40346B9C, 0x4035FDBB, 0x40378FDB,
0x403921FB, 0x403AB41B, 0x403C463A, 0x403DD85A, 0x403F6A7A,
0x40407E4C, 0x4041475C, 0x4042106C, 0x4042D97C, 0x4043A28C,
0x40446B9C, 0x404534AC, 0x4045FDBB, 0x4046C6CB, 0x40478FDB,
0x404858EB, 0x404921FB,
};
static const double
zero = 0.00000000000000000000e+00, // 0x00000000, 0x00000000
half = 5.00000000000000000000e-01, // 0x3FE00000, 0x00000000
two24 = 1.67772160000000000000e+07, // 0x41700000, 0x00000000
invpio2 = 6.36619772367581382433e-01, // 0x3FE45F30, 0x6DC9C883
pio2_1 = 1.57079632673412561417e+00, // 0x3FF921FB, 0x54400000
pio2_1t = 6.07710050650619224932e-11, // 0x3DD0B461, 0x1A626331
pio2_2 = 6.07710050630396597660e-11, // 0x3DD0B461, 0x1A600000
pio2_2t = 2.02226624879595063154e-21, // 0x3BA3198A, 0x2E037073
pio2_3 = 2.02226624871116645580e-21, // 0x3BA3198A, 0x2E000000
pio2_3t = 8.47842766036889956997e-32; // 0x397B839A, 0x252049C1
double z, w, t, r, fn;
double tx[3];
s32 e0, i, j, nx, n, ix, hx;
hx = GET_MSDW(x); /* high word of x */
ix = hx & 0x7fffffff;
if (ix <= 0x3fe921fb) { /* |x| ~<= pi/4 , no need for reduction */
y[0] = x;
y[1] = 0;
return 0;
}
if (ix < 0x4002d97c) { /* |x| < 3pi/4, special case with n=+-1 */
if (hx > 0) {
z = x - pio2_1;
if (ix != 0x3ff921fb) { // 33+53 bit pi is good enough
y[0] = z - pio2_1t;
y[1] = (z - y[0]) - pio2_1t;
} else { /* near pi/2, use 33+33+53 bit pi */
z -= pio2_2;
y[0] = z - pio2_2t;
y[1] = (z - y[0]) - pio2_2t;
}
return 1;
} else { /* negative x */
z = x + pio2_1;
if (ix != 0x3ff921fb) { // 33+53 bit pi is good enough
y[0] = z + pio2_1t;
y[1] = (z - y[0]) + pio2_1t;
} else { /* near pi/2, use 33+33+53 bit pi */
z += pio2_2;
y[0] = z + pio2_2t;
y[1] = (z - y[0]) + pio2_2t;
}
return -1;
}
}
if (ix <= 0x413921fb) { /* |x| ~<= 2^19*(pi/2), medium size */
t = fabs(x);
n = (s32) (t * invpio2 + half);
fn = (double)n;
r = t - fn * pio2_1;
w = fn * pio2_1t; /* 1st round good to 85 bit */
if (n < 32 && ix != npio2_hw[n - 1])
y[0] = r - w; /* quick check no cancellation */
else {
u32 high;
j = ix >> 20;
y[0] = r - w;
high = GET_MSDW(y[0]);
i = j - ((high >> 20) & 0x7ff);
if (i > 16) { /* 2nd iteration needed, good to 118 */
t = r;
w = fn * pio2_2;
r = t - w;
w = fn * pio2_2t - ((t - r) - w);
y[0] = r - w;
high = GET_MSDW(y[0]);
i = j - ((high >> 20) & 0x7ff);
/* 3rd iteration needed, 151 bits acc */
if (i > 49) {
t = r; // will cover all possible cases
w = fn * pio2_3;
r = t - w;
w = fn * pio2_3t - ((t - r) - w);
y[0] = r - w;
}
}
}
y[1] = (r - y[0]) - w;
if (hx < 0) {
y[0] = -y[0];
y[1] = -y[1];
return -n;
} else
return n;
}
/*
* all other (large) arguments
*/
if (ix >= 0x7ff00000) { /* x is inf or NaN */
y[0] = y[1] = x - x;
return 0;
}
/* set z = scalbn(|x|,ilogb(x)-23) */
z = SET_LSDW(z, GET_LSDW(x));
e0 = (ix >> 20) - 1046; /* e0 = ilogb(z)-23; */
z = SET_MSDW(z, ix - ((s32) (e0 << 20)));
for (i = 0; i < 2; i++) {
tx[i] = (double)((s32) (z));
z = (z - tx[i]) * two24;
}
tx[2] = z;
nx = 3;
while (tx[nx - 1] == zero)
nx--; /* skip zero term */
n = __rem_pio2(tx, y, e0, nx, 2, two_over_pi);
if (hx < 0) {
y[0] = -y[0];
y[1] = -y[1];
return -n;
}
return n;
}
double fmod(double x, double y)
{
static const double one = 1.0, Zero[] = { 0.0, -0.0, };
int n, hx, hy, hz, ix, iy, sx, i;
unsigned int lx, ly, lz;
hx = GET_MSDW(x);
lx = GET_LSDW(x);
hy = GET_MSDW(y);
ly = GET_LSDW(y);
sx = hx & 0x80000000; /* sign of x */
hx ^= sx; /* |x| */
hy &= 0x7fffffff; /* |y| */
/* purge off exception values */
if ((hy | ly) == 0 || (hx >= 0x7ff00000) || /* y=0,or x not finite */
((hy | ((ly | -ly) >> 31)) > 0x7ff00000)) /* or y is NaN */
return (x * y) / (x * y);
if (hx <= hy) {
if ((hx < hy) || (lx < ly))
return x; /* |x|<|y| return x */
if (lx == ly)
return Zero[(u32) sx >> 31]; /* |x|=|y| return x*0 */
}
/* determine ix = ilogb(x) */
if (hx < 0x00100000) { /* subnormal x */
if (hx == 0)
for (ix = -1043, i = lx; i > 0; i <<= 1)
ix -= 1;
else
for (ix = -1022, i = (hx << 11); i > 0; i <<= 1)
ix -= 1;
} else
ix = (hx >> 20) - 1023;
/* determine iy = ilogb(y) */
if (hy < 0x00100000) { /* subnormal y */
if (hy == 0)
for (iy = -1043, i = ly; i > 0; i <<= 1)
iy -= 1;
else
for (iy = -1022, i = (hy << 11); i > 0; i <<= 1)
iy -= 1;
} else
iy = (hy >> 20) - 1023;
/* set up {hx,lx}, {hy,ly} and align y to x */
if (ix >= -1022)
hx = 0x00100000 | (0x000fffff & hx);
else { /* subnormal x, shift x to normal */
n = -1022 - ix;
if (n <= 31) {
hx = (hx << n) | (lx >> (32 - n));
lx <<= n;
} else {
hx = lx << (n - 32);
lx = 0;
}
}
if (iy >= -1022)
hy = 0x00100000 | (0x000fffff & hy);
else { /* subnormal y, shift y to normal */
n = -1022 - iy;
if (n <= 31) {
hy = (hy << n) | (ly >> (32 - n));
ly <<= n;
} else {
hy = ly << (n - 32);
ly = 0;
}
}
/* fix point fmod */
n = ix - iy;
while (n--) {
hz = hx - hy;
lz = lx - ly;
if (lx < ly)
hz -= 1;
if (hz < 0) {
hx = hx + hx + (lx >> 31);
lx = lx + lx;
} else {
if ((hz | lz) == 0) /* return sign(x)*0 */
return Zero[(u32) sx >> 31];
hx = hz + hz + (lz >> 31);
lx = lz + lz;
}
}
hz = hx - hy;
lz = lx - ly;
if (lx < ly)
hz -= 1;
if (hz >= 0) {
hx = hz;
lx = lz;
}
/* convert back to floating value and restore the sign */
if ((hx | lx) == 0) /* return sign(x)*0 */
return Zero[(u32) sx >> 31];
while (hx < 0x00100000) { /* normalize x */
hx = hx + hx + (lx >> 31);
lx = lx + lx;
iy -= 1;
}
if (iy >= -1022) { /* normalize output */
hx = ((hx - 0x00100000) | ((iy + 1023) << 20));
x = DW_TO_DBL(hx | sx, lx);
} else { /* subnormal output */
n = -1022 - iy;
if (n <= 20) {
lx = (lx >> n) | ((u32) hx << (32 - n));
hx >>= n;
} else if (n <= 31) {
lx = (hx << (32 - n)) | (lx >> n);
hx = sx;
} else {
lx = hx >> (n - 32);
hx = sx;
}
x = DW_TO_DBL(hx | sx, lx);
x *= one; /* create necessary signal */
}
return x;
}
static double __sin(double x, double y, int iy)
{
static double
half = 5.00000000000000000000e-01,/* 0x3FE00000, 0x00000000 */
S1 = -1.66666666666666324348e-01, /* 0xBFC55555, 0x55555549 */
S2 = 8.33333333332248946124e-03, /* 0x3F811111, 0x1110F8A6 */
S3 = -1.98412698298579493134e-04, /* 0xBF2A01A0, 0x19C161D5 */
S4 = 2.75573137070700676789e-06, /* 0x3EC71DE3, 0x57B1FE7D */
S5 = -2.50507602534068634195e-08, /* 0xBE5AE5E6, 0x8A2B9CEB */
S6 = 1.58969099521155010221e-10; /* 0x3DE5D93A, 0x5ACFD57C */
double z, r, v;
int ix = GET_MSDW(x);
ix &= 0x7fffffff; /* high word of x */
if (ix < 0x3e400000 && (int)x == 0) /* |x| < 2**-27 */
return x; /* generate inexact */
z = x * x;
v = z * x;
r = S2 + z * (S3 + z * (S4 + z * (S5 + z * S6)));
if (!iy)
return x + v * (S1 + z * r);
else
return x - ((z * (half * y - v * r) - y) - v * S1);
}
static double __cos(double x, double y)
{
static const double
one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */
C1 = 4.16666666666666019037e-02, /* 0x3FA55555, 0x5555554C */
C2 = -1.38888888888741095749e-03, /* 0xBF56C16C, 0x16C15177 */
C3 = 2.48015872894767294178e-05, /* 0x3EFA01A0, 0x19CB1590 */
C4 = -2.75573143513906633035e-07, /* 0xBE927E4F, 0x809C52AD */
C5 = 2.08757232129817482790e-09, /* 0x3E21EE9E, 0xBDB4B1C4 */
C6 = -1.13596475577881948265e-11; /* 0xBDA8FAE9, 0xBE8838D4 */
double a, hz, z, r, qx;
int ix = GET_MSDW(x);
ix &= 0x7fffffff; /* ix = |x|'s high word */
if (ix < 0x3e400000 && (int)x == 0) /* if x < 2**27 */
return one; /* generate inexact */
z = x * x;
r = z * (C1 + z * (C2 + z * (C3 + z * (C4 + z * (C5 + z * C6)))));
if (ix < 0x3FD33333) /* if |x| < 0.3 */
return one - (0.5 * z - (z * r - x * y));
else {
if (ix > 0x3fe90000) /* x > 0.78125 */
qx = 0.28125;
else
qx = DW_TO_DBL(ix - 0x00200000, 0); /* x/4 */
hz = 0.5 * z - qx;
a = one - qx;
return a - (hz - (z * r - x * y));
}
}
double sin(double x)
{
double y[2], z = 0.0;
int ix;
ix = GET_MSDW(x);
ix &= 0x7fffffff;
if (ix <= 0x3fe921fb)
return __sin(x, z, 0);
else if (ix >= 0x7ff00000)
return x - x;
else {
int n = rem_pio2(x, y);
switch (n & 3) {
case 0:
return __sin(y[0], y[1], 1);
case 1:
return __cos(y[0], y[1]);
case 2:
return -__sin(y[0], y[1], 1);
default:
return -__cos(y[0], y[1]);
}
}
}
double cos(double x)
{
double y[2], z = 0.0;
s32 ix = GET_MSDW(x);
/* |x| ~< pi/4 */
ix &= 0x7fffffff;
if (ix <= 0x3fe921fb)
return __cos(x, z);
/* cos(Inf or NaN) is NaN */
else if (ix >= 0x7ff00000)
return x - x;
/* argument reduction needed */
else {
s32 n = rem_pio2(x, y);
switch (n & 3) {
case 0:
return __cos(y[0], y[1]);
case 1:
return -__sin(y[0], y[1], 1);
case 2:
return -__cos(y[0], y[1]);
default:
return __sin(y[0], y[1], 1);
}
}
}
int main()
{
double a;
for (a = 0.0; a < 3 * M_PI; a += 0.1)
printf("sin(%.3f)=%14.10f\n", a, sin(a));
return 0;
}