Index: /issm/trunk-jpl/src/m/mech/basalstress.m
===================================================================
--- /issm/trunk-jpl/src/m/mech/basalstress.m	(revision 24942)
+++ /issm/trunk-jpl/src/m/mech/basalstress.m	(revision 24943)
@@ -18,6 +18,11 @@
 uby=md.initialization.vy/md.constants.yts;
 
-%compute basal drag
-bx = - (md.constants.g*(md.materials.rho_ice*md.geometry.thickness+md.materials.rho_water*md.geometry.base)).^r.*(md.friction.coefficient).^2.*ubx.^s;
-by = - (md.constants.g*(md.materials.rho_ice*md.geometry.thickness+md.materials.rho_water*md.geometry.base)).^r.*(md.friction.coefficient).^2.*uby.^s;
-b  = sqrt(bx.^2+by.^2);
+%compute basal drag (S.I.)
+alpha2=(max(md.constants.g*(md.materials.rho_ice*md.geometry.thickness+md.materials.rho_water*md.geometry.base),0).^r).*(md.friction.coefficient.^2).*(ub.^(s-1));
+b  =  alpha2.*ub;
+bx = -alpha2.*ubx;
+by = -alpha2.*uby;
+
+clear alpha2
+
+end