/*************************************************************
*************************************************************
* ROUNDED TO NEAREST *
*************************************************************
*************************************************************/
double scs_cos_rn(double x){
scs_t sc1, sc2;
double resd;
int N;
#if EVAL_PERF
crlibm_second_step_taken++;
#endif
scs_set_d(sc1, x);
N = rem_pio2_scs(sc2, sc1);
N = N & 0x0000003; /* extract the 2 last bits of N */
switch (N){
case 0:
cosine(sc2);
scs_get_d(&resd, sc2);
return resd;
case 1:
sine(sc2);
scs_get_d(&resd, sc2);
return -resd;
case 2:
cosine(sc2);
scs_get_d(&resd, sc2);
return -resd;
case 3:
sine(sc2);
scs_get_d(&resd, sc2);
return resd;
default:
fprintf(stderr,"ERREUR: %d is not a valid value in s_cos \n", N);
return 0.0;
}
}
void scs_get_std( scs_ptr x){
int i;
db_number d;
scs_get_d(&d.d, x);
printf("Exception : %e \n", X_EXP);
printf("Index= %d \n Sign= %d \n Double value= %.30e \n Hex mantissa= %x %x\n",
X_IND, X_SGN, d.d, d.i[HI], d.i[LO]);
for(i=0;i<SCS_NB_WORDS;i++){
printf(" D %d : %8x %20u \n",i, X_HW[i], X_HW[i]);
}
}
double scs_tan_rn(double x){
scs_t res_scs;
double resd;
#if EVAL_PERF
crlibm_second_step_taken++;
#endif
scs_tan(x,res_scs);
scs_get_d(&resd, res_scs);
return resd;
}
double scs_atanpi_rn(double x){
/* This function does NOT compute atanpi(x) correctly if it isn't
* called in atanpi_rn()
*/
scs_t sc1;
scs_t res_scs;
db_number res;
int sign =1;
res.d = x;
if (x < 0){
sign = -1;
x *= -1;
}
scs_set_d(sc1, x);
scs_atanpi(res_scs, sc1);
scs_get_d(&res.d, res_scs);
res.d *= sign;
return res.d;
}
/*************************************************************
*************************************************************
* ROUNDED TO NEAREST
*************************************************************
*************************************************************/
double log10_rn(double x)
{
scs_t R, res1;
scs_t sc_ln2_r10_times_E;
scs_ptr inv_wi, ti;
db_number nb, nb2, wi, resd;
int i, E=0;
nb.d = x;
/* Filter cases */
if (nb.i[HI_ENDIAN] < 0x00100000){ /* x < 2^(-1022) */
if (((nb.i[HI_ENDIAN] & 0x7fffffff)|nb.i[LO_ENDIAN])==0)
/* return 1.0/0.0; */ /* log(+/-0) = -Inf */
return NInf.d;
if (nb.i[HI_ENDIAN] < 0)
/* return (x-x)/0; */ /* log(-x) = Nan */
return NaN.d;
/* Subnormal number */
E -= (SCS_NB_BITS*2); /* keep in mind that x is a subnormal number */
nb.d *=SCS_RADIX_TWO_DOUBLE; /* make x as normal number */
/* We may just want add 2 to the scs number.index */
/* may be .... we will see */
}
if (nb.i[HI_ENDIAN] >= 0x7ff00000)
return x+x; /* Inf or Nan */
/* find n, nb.d such that sqrt(2)/2 < nb.d < sqrt(2) */
E += (nb.i[HI_ENDIAN]>>20)-1023;
nb.i[HI_ENDIAN] = (nb.i[HI_ENDIAN] & 0x000fffff) | 0x3ff00000;
if (nb.d > SQRT_2){
nb.d *= 0.5;
E++;
}
/* to normalize nb.d and round to nearest */
/* +((2^4 - trunc(sqrt(2)/2) *2^4 )*2 + 1)/2^5 */
nb2.d = nb.d + norm_number.d;
i = (nb2.i[HI_ENDIAN] & 0x000fffff);
i = i >> 16; /* 0<= i <=11 */
wi.d = (11+i)*(double)0.6250e-1;
/* (1+f-w_i) */
nb.d -= wi.d;
/* Table reduction */
ti = table_ti_ptr[i];
inv_wi = table_inv_wi_ptr[i];
/* R = (1+f-w_i)/w_i */
scs_set_d(R, nb.d);
scs_mul(R, R, inv_wi);
/* sc_ln2_r10_times_E = E*log10(2) */
scs_set(sc_ln2_r10_times_E, sc_ln2_r10_ptr);
if (E >= 0){
scs_mul_ui(sc_ln2_r10_times_E, (unsigned int) E);
}else{
scs_mul_ui(sc_ln2_r10_times_E, (unsigned int) -E);
sc_ln2_r10_times_E->sign = -1;
}
/*
* Polynomial evaluation of log10(1 + R) with an error less than 2^(-130)
*/
scs_mul(res1, constant_poly_ptr[0], R);
for(i=1; i<20; i++){
scs_add(res1, constant_poly_ptr[i], res1);
scs_mul(res1, res1, R);
}
scs_add(res1, res1, ti);
scs_add(res1, res1, sc_ln2_r10_times_E);
scs_get_d(&resd.d, res1);
return resd.d;
}
static void scs_atan(scs_ptr res_scs, scs_ptr x){
scs_t X_scs, denom1_scs, denom2_scs, poly_scs, X2;
scs_t atanbhihi,atanbhilo, atanblo, atanbhi, atanb;
scs_t bsc_ptr;
db_number db;
double test;
int k, i=31;
scs_get_d(&db.d, x);
#if EVAL_PERF
crlibm_second_step_taken++;
#endif
/* test if x as to be reduced */
if (db.d > MIN_REDUCTION_NEEDED) {
/* Compute i so that x E [a[i],a[i+1]] */
if (db.d < arctan_table[i][A].d) i-= 16;
else i+=16;
if (db.d < arctan_table[i][A].d) i-= 8;
else i+= 8;
if (db.d < arctan_table[i][A].d) i-= 4;
else i+= 4;
if (db.d < arctan_table[i][A].d) i-= 2;
else i+= 2;
if (db.d < arctan_table[i][A].d) i-= 1;
else if (i<61) i+= 1;
if (db.d < arctan_table[i][A].d) i-= 1;
/* evaluate X = (x - b(i)) / (1 + x*b(i)) */
scs_set_d(bsc_ptr, arctan_table[i][B].d);
scs_mul(denom1_scs,bsc_ptr,x);
scs_add(denom2_scs,denom1_scs,SCS_ONE);
scs_sub(X_scs,x,bsc_ptr);
scs_div(X_scs,X_scs,denom2_scs);
scs_get_d(&test,X_scs);
/* Polynomial evaluation of atan(X) , X = (x-b(i)) / (1+ x*b(i)) */
scs_square(X2, X_scs);
scs_set(res_scs, constant_poly_ptr[0]);
for(k=1; k < 10; k++) {
/* we use Horner expression */
scs_mul(res_scs, res_scs, X2);
scs_add(res_scs, constant_poly_ptr[k], res_scs);
}
scs_mul(poly_scs, res_scs, X_scs);
/* reconstruction : */
/* 1st we load atan ( b[i] ) in a scs*/
scs_set_d( atanbhihi , arctan_table[i][ATAN_BHI].d);
scs_set_d( atanbhilo , arctan_table[i][ATAN_BLO].d);
scs_set_d( atanblo , atan_blolo[i].d);
scs_add(atanbhi,atanbhihi,atanbhilo);
scs_add(atanb,atanbhi,atanblo);
scs_add(res_scs,atanb, poly_scs);
return;
}
else
{ /* no reduction needed */
/* Polynomial evaluation of atan(x) */
scs_square(X2, x);
scs_set(res_scs, constant_poly_ptr[0]);
for(k=1; k < 10; k++) {
/* we use Horner expression */
scs_mul(res_scs, res_scs, X2);
scs_add(res_scs, constant_poly_ptr[k], res_scs);
}
scs_mul(res_scs, res_scs, x);
return;
}
}
