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(EXPT 10.0l0 308) failed because of computing too many powers of 10.0l

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jjgarcia 2005-03-16 13:26:30 +00:00
parent 93fa0f8a08
commit 077beb63cd
2 changed files with 17 additions and 15 deletions
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4
src/CHANGELOG
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@ -28,6 +28,10 @@ ECL 0.9f
- Where available, ECL now uses _setjmp/_longjmp for control structures. These
functions are faster, as they do not save signals.
- (EXPT 10.0l0 308) failed because the routine EXPT computed too many powers
of 10.0l0, some of which (in particular 10^512) were not required and
overflowed the machine accuracy.
* Foreign function interface (FFI):
- ext:c-uint-max and ext:c-ulong-max did not have the right bignum value.

28
src/c/num_sfun.d
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@ -138,28 +138,26 @@ cl_expt(cl_object x, cl_object y)
if (number_zerop(x)) {
if (!number_plusp(ty==t_complex?y->complex.real:y))
FEerror("Cannot raise zero to the power ~S.", 1, y);
return1(number_times(x, y));
}
if (ty == t_fixnum || ty == t_bignum) {
if (number_minusp(y)) {
z = number_negate(y);
z = cl_expt(x, z);
z = number_divide(MAKE_FIXNUM(1), z);
return1(z);
}
z = number_times(x, y);
} else if (ty != t_fixnum && ty != t_bignum) {
z = cl_log1(x);
z = number_times(z, y);
z = cl_exp(z);
} else if (number_minusp(y)) {
z = number_negate(y);
z = cl_expt(x, z);
z = number_divide(MAKE_FIXNUM(1), z);
} else {
z = MAKE_FIXNUM(1);
do {
/* INV: integer_divide outputs an integer */
if (!number_evenp(y))
z = number_times(z, x);
x = number_times(x, x);
y = integer_divide(y, MAKE_FIXNUM(2));
} while (number_plusp(y));
return1(z);
if (number_zerop(y)) break;
x = number_times(x, x);
} while (1);
}
z = cl_log1(x);
z = number_times(z, y);
z = cl_exp(z);
return1(z);
}