TINV functions

[Andre]

Dear Averyone,

The calculation for two-tailed inverse of the student`s t-distribution function presented by Excel functions like =TINV(probability, deg_freedom).

For instance: The Excel function =TINV(0.05/1223,1223-2)

Could anyone show me a manual calculation for this?

Appreciate your helps.


Cheers!

[Rich]

Post by Andre
Dear Averyone,
The calculation for two-tailed inverse of the student`s
t-distribution function presented by Excel functions like
=TINV(probability, deg_freedom).
For instance: The Excel function =TINV(0.05/1223,1223-2)
Could anyone show me a manual calculation for this?
Appreciate your helps.

If you were to ask in a group who's topic is directed to your question,
you might get a better answer.

Try one (or both) of these:

sci.math
sci.math.num-analysis

[Andre]

Hi Rich, I have posted to maths and statistics forum but do not solve the problem.

Post by Rich

Post by Andre
Dear Averyone,
The calculation for two-tailed inverse of the student`s
t-distribution function presented by Excel functions like
=TINV(probability, deg_freedom).
For instance: The Excel function =TINV(0.05/1223,1223-2)
Could anyone show me a manual calculation for this?
Appreciate your helps.

If you were to ask in a group who's topic is directed to your question,
you might get a better answer.
sci.math
sci.math.num-analysis

[Rich]

Post by Andre
Hi Rich, I have posted to maths and statistics forum but do not solve the problem.

The issue is, you are asking a math question in a group that is
supposed to be about Tcl. You are not asking a Tcl question (at least
not yet).



The second issue is you are using google groups, which really messes up
badly any quoted articles unless you manually fix the quotes before
submitting them. Consider registering for an Eternal September account
(http://www.eternal-september.org/) and utilizing a real newsreader to
access Usenet.

[Pietro Cerutti]

Post by Andre
Dear Averyone,
The calculation for two-tailed inverse of the student`s t-distribution function presented by Excel functions like =TINV(probability, deg_freedom).
For instance: The Excel function =TINV(0.05/1223,1223-2)
Could anyone show me a manual calculation for this?

A quick google search reveals that Boost implements the Student's T
distribution. Doing the inverse should be quite easy, as should be
reimplementing this in Tcl.

http://beta.boost.org/doc/libs/1_56_0/boost/math/distributions/students_t.hpp

[Christian Gollwitzer]

Post by Pietro Cerutti

Post by Andre
Dear Averyone,
The calculation for two-tailed inverse of the student`s t-distribution function presented by Excel functions like =TINV(probability, deg_freedom).
For instance: The Excel function =TINV(0.05/1223,1223-2)
Could anyone show me a manual calculation for this?

A quick google search reveals that Boost implements the Student's T
distribution. Doing the inverse should be quite easy, as should be
reimplementing this in Tcl.
http://beta.boost.org/doc/libs/1_56_0/boost/math/distributions/students_t.hpp

Well, reimplementing in Tcl requires the availability of certain special
functions (inverse beta, ...), which are not available in standard Tcl.
Fortunately, not only these are in reach with Arjen having wrapped the
cephes library, but also the student's T and it's inverse are contained
there:

http://www.netlib.org/cephes/doubldoc.html#stdtri

Christian

[Andre]

Dear All,

Crist, I dont understand translate from there. Could you translate it.

I found any web page but still not found it.

http://www.matrixlab-examples.com/t-distribution.html
http://www.matrixlab-examples.com/t-statistic.html


Anyone can get equation code from web page below:
http://www.danielsoper.com/statcalc3/calc.aspx?id=10


Thanks in advance.

Cheers!

Post by Christian Gollwitzer

Post by Pietro Cerutti

Post by Andre
Dear Averyone,
The calculation for two-tailed inverse of the student`s t-distribution function presented by Excel functions like =TINV(probability, deg_freedom).
For instance: The Excel function =TINV(0.05/1223,1223-2)
Could anyone show me a manual calculation for this?

A quick google search reveals that Boost implements the Student's T
distribution. Doing the inverse should be quite easy, as should be
reimplementing this in Tcl.
http://beta.boost.org/doc/libs/1_56_0/boost/math/distributions/students_t.hpp

Well, reimplementing in Tcl requires the availability of certain special
functions (inverse beta, ...), which are not available in standard Tcl.
Fortunately, not only these are in reach with Arjen having wrapped the
cephes library, but also the student's T and it's inverse are contained
http://www.netlib.org/cephes/doubldoc.html#stdtri
Christian

[Christian Gollwitzer]

Hi Andre,

Post by Andre
Crist, I dont understand translate from there. Could you translate it.

Please don't cripple my name. Call me "Christian". I haven't said that
there is a solution available right now, but Arjen (have you seen his
thread about cephes?) is creating a Tcl library that contains the cephes
special functions. I think that the stdtri from cepehs does the same as
TINV, so if you wait until he makes the libary public, you can use that

Post by Andre
I found any web page but still not found it.
http://www.matrixlab-examples.com/t-distribution.html

This page shows an approximation with an error below 2.5*10^-4. This is
not very precise, but if that is sufficient to you, why don't you
translate the MATLAB code given there to Tcl? It is just straightforward
math.

Christian