fixing migr/extrap demo scripts

Author: JanThorbecke

extrap/demo/README

@@ -0,0 +1,7 @@
+ The scripts in this directory can reproduce the figure in doc/OpenExtrap.pdf
+
+-1- model.scr : generates the velocity model and a zero-offset data-set that contains one non-zero trace to generate a puls response.
+
+-2- migr.scr : an example of ZO migration with different extrapolation operators
+
+-3- extrap.scr : examples how to use the extrap program

extrap/main/migr.c

@@ -426,11 +426,11 @@ int main(int argc, char *argv[])
 		vmess("extrapolation aperture         = %d", ixa);
 		if (zomigr)  {
             vmess("zero-offset migration");
-            vmess("number of depth steps     = %d", ndepth);
         }
 		vmess("minimum velocity               = %.2f", cmin);
 		vmess("maximum velocity               = %.2f", cmax);
 		vmess("dz can be as large as          = %.2f", cmin/(2*fmax));
+        vmess("number of depth steps          = %d", ndepth);
 		vmess("first model position           = %.2f", ox);
 		vmess("last model position            = %.2f", fxm);
 		vmess("orig of model (x, z)           = %.2f, %.2f", ox, oz);