Notice: On March 31, it was announced that Statalist is moving from an email list to a forum. The old list will shut down on April 23, and its replacement, statalist.org is already up and running.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

# Re: st: how to define a matrix with mathematical expression

 From Nina YIN To statalist@hsphsun2.harvard.edu Subject Re: st: how to define a matrix with mathematical expression Date Mon, 10 Sep 2012 14:37:39 +0200

```Hi Nick,

Thank you for your reply!

Does you mean that I should make these derivations into vectors and
then define them into matrix?

However, it's a big matrix with size110*110. Also I want to define the
element "x_{ij}" as

if some condition satisfied, x_{ij}= partial Di/partial Pj;

else  x_{ij}=0.

Therefore, it would be a problem if it need me to define each element by hand.

Do you have any idea about this? Thank you very much!

Best,
Nina

On Mon, Sep 10, 2012 at 2:27 PM, Nick Cox <njcoxstata@gmail.com> wrote:
> I think you are correct. If your matrix is a matrix of partial
> derivatives, you have to do any calculus derivations yourself.
>
> Nick
>
> On Mon, Sep 10, 2012 at 1:22 PM, Nina YIN <yinnina.ccer@gmail.com> wrote:
>
>> I am trying to construct a matrix with elements defined in
>> mathematical expression. For example, a m*m matrix A with elements
>> "a_{ij}"=partial Di/ partial Pj. Di (Pj) is the i-th ( j-th ) element
>> of variable D(P).
>>
>> I just know -matrix define and -mkmat, however I didn't find out that
>> these two commands could help me in this problem. Do I understand it
>> well?
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/

--
*
*   For searches and help try:
*   http://www.stata.com/help.cgi?search
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```

© Copyright 1996–2016 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   Site index