double
SECTION
__mpsin1(double x)
{
int p;
int n;
mp_no u,s,c;
double y;
p=32;
n=__mpranred(x,&u,p); /* n is 0, 1, 2 or 3 */
__c32(&u,&c,&s,p);
switch (n) { /* in which quarter of unit circle y is*/
case 0:
__mp_dbl(&s,&y,p);
return y;
break;
case 2:
__mp_dbl(&s,&y,p);
return -y;
break;
case 1:
__mp_dbl(&c,&y,p);
return y;
break;
case 3:
__mp_dbl(&c,&y,p);
return -y;
break;
}
return 0; /* unreachable, to make the compiler happy */
}
/* Compute cos() of double-length number (X + DX) as Multi Precision number and
return result as double. If REDUCE_RANGE is true, X is assumed to be the
original input and DX is ignored. */
double
SECTION
__mpcos (double x, double dx, bool reduce_range)
{
double y;
mp_no a, b, c, s;
int n;
int p = 32;
if (reduce_range)
{
n = __mpranred (x, &a, p); /* n is 0, 1, 2 or 3. */
__c32 (&a, &c, &s, p);
}
else
{
n = -1;
__dbl_mp (x, &b, p);
__dbl_mp (dx, &c, p);
__add (&b, &c, &a, p);
if (x > 0.8)
{
__sub (&hp, &a, &b, p);
__c32 (&b, &s, &c, p);
}
else
__c32 (&a, &c, &s, p); /* a = cos(x+dx) */
}
/* Convert result based on which quarter of unit circle y is in. */
switch (n)
{
case 1:
__mp_dbl (&s, &y, p);
y = -y;
break;
case 3:
__mp_dbl (&s, &y, p);
break;
case 2:
__mp_dbl (&c, &y, p);
y = -y;
break;
/* Quadrant not set, so the result must be cos (X + DX), which is also
stored in C. */
case 0:
default:
__mp_dbl (&c, &y, p);
}
LIBC_PROBE (slowcos, 3, &x, &dx, &y);
return y;
}
void
SECTION
__mptan (double x, mp_no *mpy, int p)
{
int n;
mp_no mpw, mpc, mps;
/* Negative or positive result. */
n = __mpranred (x, &mpw, p) & 0x00000001;
/* Computing sin(x) and cos(x). */
__c32 (&mpw, &mpc, &mps, p);
/* Second or fourth quarter of unit circle. */
if (n)
{
__dvd (&mpc, &mps, mpy, p);
mpy->d[0] *= -1;
}
/* tan is negative in this area. */
else
__dvd (&mps, &mpc, mpy, p);
}
