mm_root function to solve for unknows -

[Saeed Sardar]

I am trying to solve the unkown IRR using mm_root function of the moremata package. Here is my example data set

clear
input float(eps1 eps2 dps1) double prccd float IRR
 .33  .46  .02   7.66 .
  .3  .41  .08    6.2 .
 .38  .49  .13   7.71 .
 .38   .5  .35    9.9 .
 6.8  5.7  3.1   1330 .
 1.7  3.2    1    440 .
 9.7   11  2.6    999 .
10.6 11.4  2.8   1200 .
1.04 1.18  .21    183 .
 1.1 1.23  .22  36.25 .
1.35 1.54  .25   20.5 .
1.05 1.21  .25  10.99 .
  .9  1.1  .27  19.55 .
 1.2 1.36  .33  24.25 .
1.56 1.76  .42   27.8 .
 .77  .83  .27   10.7 .
1.22  1.4  .43  19.99 .
1.17 1.32  .42 18.165 .
  .9 1.12  .29     14 .
 8.9  9.4    .   1508 .
28.8 30.9 10.2    434 .
end

And the code that I am trying use is

  mata
  mata clear
  end

  
  generate IRR=.
  mata
  z=J(1,1,.)
  st_view(z,., "IRR prccd eps1 eps2 dps1")
  function s(x,p,f1,f2,dv) {
      
      return(-p+(f2-f1+(dv*x))/x^2)
  }
  for (i=1;i<=rows(z);i++) {
      r=mm_root(IRR=.,&s(),z[i,9]+epsilon(1),1-epsilon(1),1e-9,1000,z[i,2],z[i,3],z[i,4],z[i,5], z[i,6],z[i,7],z[i,8],z[i,9],z[i,10] )
      z[i,1]=IRR
  }
  end

I receive the followng error message

<istmt>: 3301 subscript invalid
r(3301);

[Joseph Coveney]

From the way you created the dataset and the way you created the Mata view of it, z will have five columns. In your call to the user-written Mata function, you make reference to up to 10 columns of the view. From the error message, it sounds like it's trying to tell you that column subscripts beyond five are out-of-range.

[Saeed Sardar]

I tried to delete the following and many other combination, but still I receive the same message.
z[i,6],z[i,7],z[i,8],z[i,9],z[i,10]

[Attaullah Shah]

Joseph is right, Your st_view creates a view onto five varaibles, while the mm_root looks for 10 columns which do not exist. See the following code

mata
  mata clear
  end

  
  generate IRR=.
  mata
  z=J(1,1,.)
  st_view(z,., "IRR prccd eps1 eps2 dps1")
  function s(x,p,f1,f2,dv) {
      
      return(-p+(f2-f1+(dv*x))/x^2)
  }
  for (i=1;i<=rows(z);i++) {
      r=mm_root(IRR=.,&s(),z[i,5]+epsilon(1),1-epsilon(1),1e-9,1000,z[i,2],z[i,3],z[i,4],z[i,5])
      z[i,1]=IRR
  }
  end

[Joseph Coveney]

I tried to delete the following and many other combination, but still I receive the same message.
z[i,6],z[i,7],z[i,8],z[i,9],z[i,10]

See here, especially the first two sentences under the first subsection.

[Saeed Sardar]

Thanks everyone, the code provided by Attaullah Shah worked for me.