Please tell me about the basics of Matrix.

[Nobuaki Michihata]

. mat A=1,2,3\4,5,6

. mat list A

A[2,3]
c1 c2 c3
r1 1 2 3
r2 4 5 6

. mat B=A[2,.]

. mat list B

symmetric B[1,1]
c1
r1 .

. /* I expected the following results.
> B[1,3]
> c1 c2 c3
> r1 4 5 6
> */
.
. capture noisily mat C=A[|2,2\2,3|]
A not found

. capture noisily mat list C
matrix C not found

. * I don't understand the reason for the error.

[Joseph Coveney]

The first error (unexpected results) is because you need more dots when specifying the range in Stata's matrix functions. So,use something like this.

mat B=A[2,....]

The second error is because you've mixed up Stata's matrix syntax with Mata's. The use of vertical lines (pipes) is Mata's submatrix-extraction syntax. You can call Mata on-the-fly from Stata in order to make use of Mata's features, and so you can use, for example, this.

mata: st_matrix("C", st_matrix("A")[|2, 2 \ 2, 3|])

.ÿ
.ÿversionÿ17.0

.ÿ
.ÿclearÿ*

.ÿ
.ÿmatrixÿdefineÿAÿ=ÿ1,ÿ2,ÿ3ÿ\ÿ4,ÿ5,ÿ6

.ÿ
.ÿmatrixÿlistÿA

A[2,3]
ÿÿÿÿc1ÿÿc2ÿÿc3
r1ÿÿÿ1ÿÿÿ2ÿÿÿ3
r2ÿÿÿ4ÿÿÿ5ÿÿÿ6

.ÿ
.ÿmatrixÿdefineÿBÿ=ÿA[2,ÿ....]

.ÿ
.ÿmatrixÿlistÿB

B[1,3]
ÿÿÿÿc1ÿÿc2ÿÿc3
r2ÿÿÿ4ÿÿÿ5ÿÿÿ6

.ÿ
.ÿmata:ÿst_matrix("C",ÿst_matrix("A")[|2,ÿ2ÿ\ÿ2,ÿ3|])

.ÿ
.ÿmatrixÿlistÿC

C[1,2]
ÿÿÿÿc1ÿÿc2
r1ÿÿÿ5ÿÿÿ6

.ÿ
.ÿexit

endÿofÿdo-file


.

[Nobuaki Michihata]

Thank you for your prompt response!
Matrix function is difficult and deep. I will study more.