Error: (execution)Matrix has not been set to a value

[twopunchman]

Hello,

I was trying to do gradient descent  in SAS. Below is my Code. I got "Matrix has not been set to a value" error and it said the Matrix Jtheta_new has not been set to a value. I searched a lot but still can't fix it. Any idea? Thank you.

options fullstimer;proc iml;
    reset deflib=sashelp;
    use class;
    read all var {weight height} into me;
    m = nrow(me);

    *scaling feature;
    s1 = max(me[,1])-min(me[,1]);
    s2 = max(me[,2])-min(me[,2]);
    mean_s1 = mean(me[,1]);
    mean_s2 = mean(me[,2]);
    me[,1] = (me[,1]-mean_s1)/s1;
    me[,2] = (me[,2]-mean_s2)/s2;
    *scaling feature;
      theta_0 = 0;
    theta_1 = 0;
    x0 = 1;
    ov = 10;
    alpha = 0.03;
    *print me;
    rec = 0;
　　
    do while (ov>0.000000001);
 
    theta_0Old = theta_0;
    theta_1Old = theta_1;
    *compute old residual and collect data to plot r*numOfIteration;
    rec = rec + 1;
    r2 = 0;
    do i=1 to m;
            residual_tt =(theta_0Old*x0 + theta_1Old*me[i,2]) - me[i,1];
            r2 = r2+residual_tt*residual_tt;
    end;
    Jtheta = r2/2/m;
    xy = xy//(rec||Jtheta);
    *compute old residual and collect data to plot r*numOfIteration;

        res = 0; res_1 = 0;
        do i=1 to m;
            residual_0 =(theta_0Old*x0 + theta_1Old*me[i,2]) - me[i,1];
            res = res + (residual_0*x0);
            res_1 = res_1 + (residual_0*me[i,2]);
        end;
                theta_0 = theta_0Old - alpha*res/m;
        theta_1 = theta_1Old - alpha*res_1/m;

    *update residual and decide whether it's convergence;
        r2 = 0;
        do i=1 to m;
            residual_tt =(theta_0*x0 + theta_1*me[i,2]) - me[i,1];
            r2 = r2+residual_tt*residual_tt;
        end;
        Jtheta_new = r2/2/m;
        ov = abs(Jtheta_new - Jtheta);
    *update residual and decide whether it's convergence;    
    end;
    print ov;
    call pgraf(xy,'*','x','y','mmmmm');

    theta_0_last = theta_0*s1+mean_s1-mean_s2*s1*theta_1/s2;
    theta_1_last = theta_1*s1/s2;
    print theta_0_last theta_1_last;
    run;
quit;

[PeterClemmensen · Accepted solution]

Welcome to the SAS Community 🙂

The code works fine on my site and gives a seemingly usable result?

Remember however, that you do not want the Run Statement at the bottom. The Quit statement is enough.

[twopunchman]

Thank you so much! It seems I misspelled a variable name in SAS. LOL. Also thank you for your suggestion about the run statement.

[PeterClemmensen]

Anytime. Glad you found your answer 🙂

[Rick_SAS]

If I may offer two suggestions: 

1. Do not use RESET deflib=Sashelp;

    If you try to write a data set you will get an error message the says you do not have write permission for that library.

   Instead, keep RESET deflib=WORK (the default) and use the two-level data set name when you want to read data. For example,

   use sashelp.class;

2. The PGRAF routine produces ancient line-plot output. Use the newer ODS graphics, such as 

title 'mmmmm';
call series(xy[,1],xy[,2]) label={'x' 'y'} ;