double m_Array[iArrayWidth][iArrayHeight];
//.....
// filling m_Array with value
//....

ap::real_2d_array xy;
xy.setlength(iArrayWidth, iArrayHeight);

for ( int i = 0; i < iArrayHeight; i++ )
{
   for ( int j = 0; j < iArrayWidth; j++ )
   {
      xy(i,j) = m_Array[i][j];
   }
}

// pass to the idwbuildmodifiedshepard

ap::real_2d_array xy;
xy.setlength(m_iArrayHeight, m_iArrayWidth);

for ( int i = 0; i < m_iArrayHeight; i++ )
{
   for ( int j = 0; j < m_iArrayWidth; j++ )
   {
      xy(i*j,0) = XXX;
      xy(i*j,1) = m_ppArray[i][j].dValue;
   }
}

ap::real_2d_array xy;
xy.setlength(NumberOfPoints, NumberOfCoordinates+1); // NumberOfCoordinates=3, for example

for ( int i = 0; i < NumberOfPoints; i++ )
{
    xy(i,0) = x[i]; // x-value
    xy(i,1) = y[i]; // y-value
    xy(i,2) = z[i]; // z-value
    xy(i,3) = f[i]; // function value
}
}

xy.setlength(m_iArrayHeight * m_iArrayWidth, 3);

int k = 0;
for ( int i = 0; i < m_iArrayHeight; i++ )
{
   for ( int j = 0; j < m_iArrayWidth; j++ )
   {
      xy(k, 0) = m_ppArray[i][j].point.x;
      xy(k, 1) = m_ppArray[i][j].point.y;
      xy(k, 2) = m_ppArray[i][j].dValue;
      k++;
   }
}

k = 0;
for ( int i = 0; i < m_iArrayHeight; i++ )
{
   for ( int j = 0; j < m_iArrayWidth; j++ )
   {
      double val = Z.q(k++, 2);
   }
}

ap::real_1d_array x;
idwinterpolant z1;
int n = m_iArrayWidth * m_iArrayHeight;

idwbuildmodifiedshepard(xy, n, 2, 1, 15, 25, z1);

x.setlength(nx);

for( int i = 0; i < n; i++ )
{
   x(0) = xy(i, 2);
   //ap::vmove(&x(0), 1, &xy(i, 2), 1, ap::vlen(0,nx-1));
   double val = idwcalc(z1, x);
   idwerrors = ap::fp_neq(val, xy(i,nx));
}