Displaying 10 results from an estimated 10 matches for "k_small_max".
2020 Jan 14
2
[R] choose(n, k) as n approaches k
...at 16:21 , Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
>
> On 14/01/2020 10:07 a.m., peter dalgaard wrote:
>> Yep, that looks wrong (probably want to continue discussion over on R-devel)
>> I think the culprit is here (in src/nmath/choose.c)
>> if (k < k_small_max) {
>> int j;
>> if(n-k < k && n >= 0 && R_IS_INT(n)) k = n-k; /* <- Symmetry */
>> if (k < 0) return 0.;
>> if (k == 0) return 1.;
>> /* else: k >= 1 */
>> if n is a near-integer, then k can...
2020 Jan 14
1
[R] choose(n, k) as n approaches k
Yep, that looks wrong (probably want to continue discussion over on R-devel)
I think the culprit is here (in src/nmath/choose.c)
if (k < k_small_max) {
int j;
if(n-k < k && n >= 0 && R_IS_INT(n)) k = n-k; /* <- Symmetry */
if (k < 0) return 0.;
if (k == 0) return 1.;
/* else: k >= 1 */
if n is a near-integer, then k can become non-integer and negative. In your case,
n ==...
2020 Jan 13
3
choose(n, k) as n approaches k
This struck me as incorrect:
> choose(3.999999, 4)
[1] 0.9999979
> choose(3.9999999, 4)
[1] 0
> choose(4, 4)
[1] 1
> choose(4.0000001, 4)
[1] 4
> choose(4.000001, 4)
[1] 1.000002
Should base::choose(n, k) check whether n is within machine precision of k and return 1?
Thanks,
Erik
***
sessionInfo()
R version 3.6.0 beta (2019-04-15 r76395)
Platform: x86_64-apple-darwin15.6.0
2020 Jan 13
3
choose(n, k) as n approaches k
This struck me as incorrect:
> choose(3.999999, 4)
[1] 0.9999979
> choose(3.9999999, 4)
[1] 0
> choose(4, 4)
[1] 1
> choose(4.0000001, 4)
[1] 4
> choose(4.000001, 4)
[1] 1.000002
Should base::choose(n, k) check whether n is within machine precision of k and return 1?
Thanks,
Erik
***
sessionInfo()
R version 3.6.0 beta (2019-04-15 r76395)
Platform: x86_64-apple-darwin15.6.0
2020 Jan 14
4
[R] choose(n, k) as n approaches k
...ncan at gmail.com> wrote:
>>>
>>> On 14/01/2020 10:07 a.m., peter dalgaard wrote:
>>>> Yep, that looks wrong (probably want to continue discussion over on R-devel)
>>>> I think the culprit is here (in src/nmath/choose.c)
>>>> if (k < k_small_max) {
>>>> int j;
>>>> if(n-k < k && n >= 0 && R_IS_INT(n)) k = n-k; /* <- Symmetry */
>>>> if (k < 0) return 0.;
>>>> if (k == 0) return 1.;
>>>> /* else: k >= 1 */
>...
2009 Dec 15
3
RFC: lchoose() vs lfactorial() etc
lgamma(x) and lfactorial(x) are defined to return
ln|Gamma(x)| {= log(abs(gamma(x)))} or ln|Gamma(x+1)| respectively.
Unfortunately, we haven't chosen the analogous definition for
lchoose().
So, currently
> lchoose(1/2, 1:10)
[1] -0.6931472 -2.0794415 NaN -3.2425924 NaN -3.8869494
[7] NaN -4.3357508 NaN -4.6805913
Warning message:
In
2020 Jan 14
0
[R] choose(n, k) as n approaches k
On 14/01/2020 10:07 a.m., peter dalgaard wrote:
> Yep, that looks wrong (probably want to continue discussion over on R-devel)
>
> I think the culprit is here (in src/nmath/choose.c)
>
> if (k < k_small_max) {
> int j;
> if(n-k < k && n >= 0 && R_IS_INT(n)) k = n-k; /* <- Symmetry */
> if (k < 0) return 0.;
> if (k == 0) return 1.;
> /* else: k >= 1 */
>
> if n is a near-integer, then k can become non-in...
2020 Jan 14
0
[R] choose(n, k) as n approaches k
...rdoch <murdoch.duncan at gmail.com> wrote:
>>
>> On 14/01/2020 10:07 a.m., peter dalgaard wrote:
>>> Yep, that looks wrong (probably want to continue discussion over on R-devel)
>>> I think the culprit is here (in src/nmath/choose.c)
>>> if (k < k_small_max) {
>>> int j;
>>> if(n-k < k && n >= 0 && R_IS_INT(n)) k = n-k; /* <- Symmetry */
>>> if (k < 0) return 0.;
>>> if (k == 0) return 1.;
>>> /* else: k >= 1 */
>>> if n i...
2020 Jan 15
1
[R] choose(n, k) as n approaches k
...t;>>
>>>>> On 14/01/2020 10:07 a.m., peter dalgaard wrote:
>>>>>> Yep, that looks wrong (probably want to continue discussion over on R-devel)
>>>>>> I think the culprit is here (in src/nmath/choose.c)
>>>>>> if (k < k_small_max) {
>>>>>> int j;
>>>>>> if(n-k < k && n >= 0 && R_IS_INT(n)) k = n-k; /* <- Symmetry */
>>>>>> if (k < 0) return 0.;
>>>>>> if (k == 0) return 1.;
>>>>>>...
2020 Jan 14
0
[R] choose(n, k) as n approaches k
...t; wrote:
>>>>
>>>> On 14/01/2020 10:07 a.m., peter dalgaard wrote:
>>>>> Yep, that looks wrong (probably want to continue discussion over on R-devel)
>>>>> I think the culprit is here (in src/nmath/choose.c)
>>>>> if (k < k_small_max) {
>>>>> int j;
>>>>> if(n-k < k && n >= 0 && R_IS_INT(n)) k = n-k; /* <- Symmetry */
>>>>> if (k < 0) return 0.;
>>>>> if (k == 0) return 1.;
>>>>> /* else: k...