integration.</td>
    </tr>
<tr><td><tt>real*8&nbsp;math_dint2d_gk(func,xmin,xmax,nx,ymin,ymax,ny,aerr)</tt></td>
    <td>Integrate 2D real*8 function using Gauss-7pk+Kronrod-13pt.</td>
    </tr>
</table>

<p>Integrate Dirac delta-function: $\int f_1(r) \delta(f_2(r))\ dr$ in 2D and
3D space. [J.Comp.Phys. 207, 28 (2005)].

<br><tt>real*8 math_dint2d_delta(f1,f2, xmin,xmax,nx, ymin,ymax,ny)</tt>
<br><tt>real*8 math_dint3d_delta(f1,f2, xmin,xmax,nx, ymin,ymax,ny,
        zmin,zmax,nz)</tt>

<p>Solve quadrati