How to pass the scalar to arguments of the mata function?

[Kazuto Sumita]

Dear colleagues:

I run the following program. However, following error appeared.

. mata: wx("distance_smat", "y_m", "hage_0", 2);
wx(): 3301 subscript invalid
<istmt>: - function returned error


I assume that there is a problem when I pass the real scalar "2" to the argument of void function wx.

It would be great if somebody suggested the way to correct the error.

Thanks in advance.

Kazuto

#delimit;
/*** mata session ***/


mata;
void wx(string scalar A, string scalar B, string scalar C, real scalar d_km){; 

    /* Obtain and put Stata matrices */
    distance_mat = st_matrix(A);

    x_mat = st_matrix(B);

    if_mat = st_matrix(C); 

    nob = rows(distance_mat);

    dstm1 = J(nob, nob, 0); 
    dstm2 = J(nob, nob, 0); 
    dstm1_invdist= J(nob, nob, 0); 


    for (i=1; i<=nob; i++) {;
        k= i+1;
        for (j=k; j<=nob; j++) {;
            if (distance_mat[i,j]<d_km) {;    
                dstm1[i,j] = 1;
                dstm1_invdist = 1/distance_mat[i,j];
            };
        };
    };

    /* save */
    st_matrix("w1_x", w1_x);
    st_matrix("w_invdist_x", w_invdist_x);

    st_matrix("nb_ratio", nb_ratio);
};
end;

/**** stata part ***/
matrix distance_smat = distance_mat+distance_mat';

mkmat lease_rate_kanri, matrix(y_m);

mkmat hage_0 , matrix(hage_0_v);

mata: wx("distance_smat", "y_m", "hage_0", 2);

[Joseph Coveney]

. . . following error appeared.

. . . wx(): 3301 subscript invalid . . .

I assume that there is a problem when I pass the real scalar "2" to the argument of void function wx.

No.

When i is equal to nob, j is equal to nob + 1 and distance_mat[i,j] etc. have an invalid subscript.

[Kazuto Sumita]

Dear Joseph:
Thanks a lot!
Kazuto

[Kazuto Sumita]

I changed the loop parts as below:

 
    for (i=1; i<=nob-1; i++) {;         k= i+1;         for (j=k; j<=nob; j++) {;             if (distance_mat[i,j]<d_km) {;                     dstm1[i,j] = 1;                 dstm1_invdist[i,j] = 1/distance_mat[i,j];             };          };     };

But I have the same error.

mata: wx("distance_smat", "y_m", "hage_0", 2);
                    wx():  3301  subscript invalid
                 <istmt>:     -  function returned error
r(3301);

[William Lisowski]

Actually, I agreed with Joseph's comment in post #2, but a closer look at the syntax description of the for statement tells us that when j is set to nob+1 the contents of the for loop over j will not be executed. So the problem must lie elsewhere.

However, I am not seeing where the problem might be. The following stripped-down version of your code runs without an error, and yet there are no obvious subscripts elsewhere in your code.

#delimit;
/*** mata session ***/


mata;
mata drop wx()
void wx(real scalar d_km){;

    nob = 4;

    distance_mat = J(nob, nob, 42)
    
    dstm1 = J(nob, nob, 0);
    dstm1_invdist= J(nob, nob, 0);


    for (i=1; i<=nob; i++) {;
        k= i+1;
        for (j=k; j<=nob; j++) {;
            if (distance_mat[i,j]<d_km) {;    
                dstm1[i,j] = 1;
                dstm1_invdist[i,j] = 1/distance_mat[i,j];
            };
        };
    };

};
end;

/**** stata part ***/

mata: wx(666);

I am not convinced you have shown the actual code you ran, because in

    /* save */
    st_matrix("w1_x", w1_x);
    st_matrix("w_invdist_x", w_invdist_x);

    st_matrix("nb_ratio", nb_ratio);

you save three matrices that were nowhere created, and because in

dstm1_invdist = 1/distance_mat[i,j];

you lack subscripts on the matrix dstm1_invdist.

Note that I added mata drop wx() to the code: is is possible your redefinitions of wx() are being ignored because wx() already exists from an earlier invocation in your session?

[Kazuto Sumita]

Dear William

I was careless to forget the subscripts.

I noticed that I mistook the name of the variable in the argument and correct the following parts from

mata: wx("distance_smat", "y_m", "hage_0", 2);

to

mata: wx("distance_smat", "y_m", "hage_0_v", 2);

After correcting those, program worked successfully.

Thanks for your comments!

Kazuto

#delimit;
/*** mata session ***/

mata;
void wx(string scalar A, string scalar B, string scalar C, real scalar d_km){; 

    /* Obtain and put Stata matrices */
    distance_mat = st_matrix(A);

    x_mat = st_matrix(B);

    if_mat = st_matrix(C); 

    nob = rows(distance_mat);

    dstm1 = J(nob, nob, 0); 
    dstm2 = J(nob, nob, 0); 
    dstm1_invdist= J(nob, nob, 0); 


    for (i=1; i<=nob-1; i++) {;
        k= i+1;
        for (j=k; j<=nob; j++) {;
            if (distance_mat[i,j]<d_km) {;    
                dstm1[i,j] = 1;
                dstm1_invdist[i,j] = 1/distance_mat[i,j];
            };
        };
    };

    /* save */
    st_matrix("w1_x", w1_x);
    st_matrix("w_invdist_x", w_invdist_x);

    st_matrix("nb_ratio", nb_ratio);
};
end;

/**** stata part ***/
matrix distance_smat = distance_mat+distance_mat';

mkmat lease_rate_kanri, matrix(y_m);

mkmat hage_0 , matrix(hage_0_v);

mata: wx("distance_smat", "y_m", "hage_0_v", 2);

[Joseph Coveney]

Yeah,

for (j=k; j<=nob; j++) {

won't execute when j starts out greater than nob.

A couple of observations.

1. The error apparently is akin to this:

clear *

mata:
mata set matastrict on

void function test1(string scalar matrix_name) {
    real matrix MyMatrix
    MyMatrix = st_matrix(matrix_name)
    MyMatrix
}

test1("NoSuchMatrix")

end

exit

That executes without any error. I would have expected some kind of "Stata matrix not found" kind of error.

2. This does give an error:

mata:
mata clear
// mata set matastrict on

void function test2() {
    st_matrix("w1_x", w1_x)
}

test2()

end

exit

So, as William observed, where do those Mata matrices come from? Are they global?