Make (acos 1) return exact zero
#621
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Previously we had
stklos> (acos 1)
0.0
stklos> (asin 0)
0
Hm, we have anice precise result for `(asin 0)`, why not for
`(acos 1)`? It's because for asin, we have:
```
case tc_integer: if (z == MAKE_INT(0)) return MAKE_INT(0);
return asin_real(INT_VAL(z));
```
and for acos, we were also testing for exact zero, and then we
returned inexact pi/2:
```
case tc_integer: if (z == MAKE_INT(0)) return div2(double2real(MY_PI),
MAKE_INT(2));
```
But that's not necessary, because `acos_real` will do that anyway. And
we were not testing for the nice case of `(acos 1)`. Now we do that.
One test was also adjusted.
jpellegrini
changed the title
(acos 1) return exact zero
|
Hi @jpellegrini, That's perfect. Thanks. |
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Previously we had
Hm, we have anice precise result for
(asin 0), why not for(acos 1)? It's because for asin, we have:and for acos, we were also testing for exact zero, and then we returned inexact pi/2:
But that's not necessary, because
acos_realwill do that anyway. And we were not testing for the nice case of(acos 1). Now we do that.One test was also adjusted.