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passing 2-d array to function

varuniitb (8)
hi
i was trying to pass the following 2-dimensional array to a function called jac_inv 
 
 
jac_inv(jac,3);

where jac is a 3x3 matrix
function is as follows:
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void jac_inv(int *jac, int m)
    {
     double determinant=0.0;

          for(i=0;i<m;i++)
          {
              for(j=0;j<m;j++)
              {
                  j_inv[i][j]=jac[i][j];
              }
          }
          for(i=0;i<m;i++)
          {
            determinant = determinant + (j_inv[0][i]*(j_inv[1][(i+1)%n]*j_inv[2][(i+2)%n] - j_inv[1][(i+2)%n]*j_inv[2][(i+1)%n]));
          }
          i=0;
          j=0;
           for(i=0;i<m;i++)
          {
              for(j=0;j<m;j++)
              {
                  j_inv[i][j]=(((j_inv[(i+1)%n][(j+1)%n] * j_inv[(i+2)%n][(j+2)%n]) - (j_inv[(i+1)%n][(j+2)%n]*j_inv[(i+2)%n][(j+1)%n]))/ determinant);
              }
          }


      }



However,I get the following error

invalid types 'int[int]' for array subscripts

please do tell me the exact problem. is it with regard to passing a multi dimensional array to a function?
please recommend changes in my code...
vlad from moscow (6539)
You shall define the function as

void jac_inv(int ( *jac )[3], int m );

varuniitb (8)
thanks for the reply
i have made the changes but it now prompts a new error

undefined reference to 'jac_inv(double  (*) [3], int )

here is my full program
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#include<iostream>
#include<fstream>
#include<cmath>
#include<cstdlib>
using namespace std;
void jac_inv (double jac[3][3],int m);
void update_delx (double j_inv[3][3],double f[3],int m);
double j_inv[3][3],delx[3],x[3],f[3];
int m,a,b,c,i,n=3,j;

main()
{
    double r1,r2,is,id,v0,v1,v2,vt,g1,g2,jac[3][3],t=0.0,nor=0.0,norm,delt,eph,expv2;
    double T=1.0/50.0;
    delt=T/100;
    eph = 1.0e-6;
    r1 = 1.0e3;
    r2 = 1.0e3;
    is = 1.0e-14;
    vt = 26.0e-3;
    v0 = 5.0;

    x[0] = 0.0;
    x[1] = 0.0;
    x[2] = 0.0e-3;

    update:
      v1 = x[0];
      v2 = x[1];
      id = x[2];
      expv2 = exp(v2/vt);

    g1=1.0/r1;
    g2=1.0/r2;

    v1=v0*sin(2*3.14*50*t);

    // create the jacobian matrix
       jac[0][0] =  g1;
       jac[0][1] = -g1;
       jac[0][2] =  1.0;

       jac[1][0] = -g1;
       jac[1][1] =  g1 + g2 + (is/vt)*expv2;
       jac[1][2] =  0.0; v1 = x[0];

       jac[2][0] = 1.0;
       jac[2][1] = 0.0;
       jac[2][2] = 0.0;

    //compute f-minus matrix
    f[0] =  id+g1*(v1-v2);
    f[1] =  g1*(v2-v1) + g2*v2 + is*(expv2 - 1.0);
    f[2] =  v1 - v0;
    for(a=0;a<3;a++)
      {
        f[a]=-1.0*f[a];
      }
    //check norm
    for(b=0;b<3;b++)
      {
        nor= f[b]*f[b] + nor;
      }
    norm=sqrt(nor);
    if (norm < eph)
      {
        cout << v2 << " " << -1.0*id << "\n";
        t=t+delt;
        if (t>T)
            exit;
        else
            goto update;
      }


      jac_inv(jac,3);


          update_delx(j_inv,f,3);

goto update;
}


void jac_inv(int (*jac)[3], int m)
    {
     double determinant=0.0;

          for(i=0;i<m;i++)
          {
              for(j=0;j<m;j++)
              {
                  j_inv[i][j]=jac[i][j];
              }
          }
          for(i=0;i<m;i++)
          {
            determinant = determinant + (j_inv[0][i]*(j_inv[1][(i+1)%n]*j_inv[2][(i+2)%n] - j_inv[1][(i+2)%n]*j_inv[2][(i+1)%n]));
          }
          i=0;
          j=0;
           for(i=0;i<m;i++)
          {
              for(j=0;j<m;j++)
              {
                  j_inv[i][j]=(((j_inv[(i+1)%n][(j+1)%n] * j_inv[(i+2)%n][(j+2)%n]) - (j_inv[(i+1)%n][(j+2)%n]*j_inv[(i+2)%n][(j+1)%n]))/ determinant);
              }
          }


      }







 void update_delx(int (*j_inv)[3],int *f,int m)
   {
       delx[0]=0.0;
       delx[1]=0.0;
       delx[2]=0.0;
       double k=0.6;
       for(i=0;i<m;i++)
          {
              for(j=0;j<m;j++)
              {
                  delx[i]=delx[i]+j_inv[i][j]*f[j];
              }
             for(c=0;c<3;c++)
             {
                 x[c]=x[c]+k*delx[c];
             }
         }

}
vlad from moscow (6539)
You changed the first declaration of the function but forgot to change its declaration in the its definition. so you have

void jac_inv (double jac[3][3],int m);

and

void jac_inv(int (*jac)[3], int m)


Last edited on
varuniitb (8)
thank you very much vlad
problem solved!!
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