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From |
"Sergiy Radyakin" <serjradyakin@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: Function el() fails |

Date |
Sun, 17 Aug 2008 17:45:25 -0400 |

Thank you, Scott, this was helpful. Perhaps the only wish I have now is to have more meaningful error messages, e.g. instead of "type mismatch" the Ideal Stata might have responded: "Type mismatch in expression el(p,1,1), expected argument of type: matrix, found argument of type: variable". But may be I am too spoiled by modern days compilers, that try to help programmers every step of the way. Best regards, Sergiy Radyakin On 8/15/08, Scott Merryman <scott.merryman@gmail.com> wrote: > You could use the pseudofunction -matrix()- to force the term p to be > interpreted as a matrix (see [P] page 262, "Name conflicts in > expressions (namespaces)" and G Kolev's "Stata tip 31: Scalar or > variable? The problem of ambiguous names", SJ 6,2). > > dis el(matrix(p),1,1) > > Scott > > > On Fri, Aug 15, 2008 at 4:54 PM, Sergiy Radyakin <serjradyakin@gmail.com> wrote: > > Dear All, > > > > after investigating why my program sometimes breaks, I have found a > > problem (observed in Stata 9 and Stata 10 for Windows) with the > > function el(matrixname, row, col ), which could be reproduces with the > > following sequence of commands: > > > > > > // ----- BEGIN ------- > > sysuse auto > > > > matrix p=1 > > matrix a=p > > > > matrix dir > > > > matrix list a > > di a[1,1] > > di el(a,1,1) > > > > matrix list p > > di p[1,1] > > di el(p,1,1) > > // ----- END ------- > > > > According to the help file for Stata 9: > > > > el(A,i,j) the i,j element of A (same as A[i,j]) > > > > Note that the program above works for matrix name "a" and not "p". > > This made it difficult to identify the problem. Because the problem is > > observed for some datasets and not for others. > > > > It seems that the namespace of variables and matrix names in Stata is > > overlapping. > > I've met the messages earlier regarding what namespaces are shared, > > but I can't find them at the moment. The manual explicitly defines the > > term "namespace" in the [P] matrix, (page 235 in 10th edition). It > > also mentions that there is a single namespace for scalars and > > matrices, however it does mention variables in a rather confusing > > statement: > > > > "Scalars and matrices share the same namespace; i.e., scalars and > > matrices may have the same names as variables in the dataset, etc., > > but they cannot have the same names as each other." > > > > Confusion here is that indeed Stata allows me to have a matrix with > > the same name as a variable, but I'd really like the built-in commands > > and functions to be able to WORK with that matrix. (Function el() as > > all functions in Stata is built-in). > > > > I wonder if anyone could elaborate on which namespaces are shared in > > Stata, in particular: > > > > variables > > locals > > globals > > scalars > > matrices > > programs > > classes > > all sort of mata objects > > all sort of graphics related styles, patterns, etc > > .... > > [not sure how long the list is, but the above list is definitely not complete] > > > > I am not sure that the problem above is an intended behavior. In any > > case it makes the case that el(a,1,1) is NOT equivalent to A[1,1] > > against what the help file says. > > If this is not an intended behaviour, can this be fixed? > > > > Thank you, > > Sergiy Radyakin > > > > CC: Stata Technical Support > * > * 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/

**References**:**st: Function el() fails***From:*"Sergiy Radyakin" <serjradyakin@gmail.com>

**Re: st: Function el() fails***From:*"Scott Merryman" <scott.merryman@gmail.com>

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