gorithm based on Camembert model [3], please visit the script <a href="MGNFWI_camenbert.html">MGNFWI_camenbert.html</a> for detail
         </p>
         <p>true model and initial model</p><pre class="codeinput">z = 0:10:1000;
x = 0:10:1000;
[o,d,n] = grid2odn(z,x);
[zz,xx] = ndgrid(z,x);
m0 = 2500 + 0*xx;

<span class="comment">% circular perturbation with radius 250 m and strenth 10%</span>
dv = 0*xx; dv((xx-500).^2 + (zz-500).^2 &lt;= 250^2) = .1*2500;
m  = m0 + dv;
figure(1);imagesc(x,z,m);caxis([2250,2