M_APM apm_get(struct DeltaVariable *v)
{
M_APM r = m_apm_init();
if(v->type == DELTA_TYPE_NUMBER)
m_apm_set_double(r, delta_cast_number(v));
else {
int release;
struct DeltaVariable *arg = delta_cast_string(v, &release);
if(release)
m_apm_set_string(r, arg->value.ptr);
else
m_apm_set_string(r, delta_copy_string(arg->value.ptr));
}
return r;
}
static M_APM Bget(lua_State *L, int i)
{
LL=L;
switch (lua_type(L,i))
{
case LUA_TNUMBER:
{
M_APM x=Bnew(L);
m_apm_set_double(x,lua_tonumber(L,i));
lua_replace(L,i);
return x;
}
case LUA_TSTRING:
{
M_APM x=Bnew(L);
m_apm_set_string(x,(char*)lua_tostring(L,i));
lua_replace(L,i);
return x;
}
default:
return *((void**)luaL_checkudata(L,i,MYTYPE));
}
return NULL;
}
void m_apm_reciprocal(M_APM rr, int places, M_APM aa)
{
M_APM last_x, guess, tmpN, tmp1, tmp2;
int ii, bflag, dplaces, nexp, tolerance;
if (aa->m_apm_sign == 0)
{
M_apm_log_error_msg(M_APM_RETURN,
"Warning! ... \'m_apm_reciprocal\', Input = 0");
M_set_to_zero(rr);
return;
}
last_x = M_get_stack_var();
guess = M_get_stack_var();
tmpN = M_get_stack_var();
tmp1 = M_get_stack_var();
tmp2 = M_get_stack_var();
m_apm_absolute_value(tmpN, aa);
/*
normalize the input number (make the exponent 0) so
the 'guess' below will not over/under flow on large
magnitude exponents.
*/
nexp = aa->m_apm_exponent;
tmpN->m_apm_exponent -= nexp;
m_apm_set_double(guess, (1.0 / m_apm_get_double(tmpN)));
tolerance = places + 4;
dplaces = places + 16;
bflag = FALSE;
m_apm_negate(last_x, MM_Ten);
/* Use the following iteration to calculate the reciprocal :
X = X * [ 2 - N * X ]
n+1
*/
ii = 0;
while (TRUE)
{
m_apm_multiply(tmp1, tmpN, guess);
m_apm_subtract(tmp2, MM_Two, tmp1);
m_apm_multiply(tmp1, tmp2, guess);
if (bflag)
break;
m_apm_round(guess, dplaces, tmp1);
/* force at least 2 iterations so 'last_x' has valid data */
if (ii != 0)
{
m_apm_subtract(tmp2, guess, last_x);
if (tmp2->m_apm_sign == 0)
break;
/*
* if we are within a factor of 4 on the error term,
* we will be accurate enough after the *next* iteration
* is complete.
*/
if ((-4 * tmp2->m_apm_exponent) > tolerance)
bflag = TRUE;
}
m_apm_copy(last_x, guess);
ii++;
}
m_apm_round(rr, places, tmp1);
rr->m_apm_exponent -= nexp;
rr->m_apm_sign = aa->m_apm_sign;
M_restore_stack(5);
}
void m_apm_set_double_mt(M_APM atmp,double dd)
{
m_apm_enter();
m_apm_set_double(atmp,dd);
m_apm_leave();
}
