Talk:Welch's t-test: Difference between revisions
Content added Content deleted
| Line 853: | Line 853: | ||
For the record, here is a quick Stata translation of this betain implementation. |
For the record, here is a quick Stata translation of this betain implementation. |
||
The original C code can be simplified in several places using shortcuts (it could be simplified even more in C). Also, ifault is not used here: instead, the function returns a missing value if the arguments are invalid. |
The original C code can be simplified in several places using shortcuts (it could be simplified even more in C). Also, ifault is not used here: instead, the function returns a missing value if the arguments are invalid. And log(beta(p,q)) is computed inside betain, rather than passed as an argument. |
||
<lang stata>mata |
<lang stata>mata |
||
| Line 860: | Line 860: | ||
Modified 28dec2017 |
Modified 28dec2017 |
||
Author: |
Author: |
||
Original |
Original FORTRAN77 version by KL Majumder, GP Bhattacharjee. |
||
C version by John Burkardt. |
C version by John Burkardt. |
||
Stata version by Jean-Claude Arbaut |
Stata version by Jean-Claude Arbaut |
||
*/ |
*/ |
||
function betain(x,p,q |
function betain(x,p,q) { |
||
| ⚫ | |||
/* Check the input arguments. */ |
/* Check the input arguments. */ |
||
if (p<=0 | q<=0 | x<0 | x>1) return(.) |
if (p<=0 | q<=0 | x<0 | x>1) return(.) |
||
/* Special cases. */ |
/* Special cases. */ |
||
if (x==0 | x==1) { |
if (x==0 | x==1) { |
||
| Line 875: | Line 873: | ||
} |
} |
||
| ⚫ | |||
lnbeta = lngamma(p)+lngamma(q)-lngamma(p+q) |
|||
/* Change tail if necessary and determine S. */ |
/* Change tail if necessary and determine S. */ |
||
psq = p+q |
psq = p+q |
||
| Line 906: | Line 907: | ||
if (temp<=acu & temp<=acu*value) { |
if (temp<=acu & temp<=acu*value) { |
||
value = value*exp(pp*log(xx)+(qq-1)*log(cx)- |
value = value*exp(pp*log(xx)+(qq-1)*log(cx)-lnbeta)/pp |
||
return(indx?1-value:value) |
return(indx?1-value:value) |
||
} |
} |
||