Index: /issm/trunk/src/m/model/plot/arrow.m
===================================================================
--- /issm/trunk/src/m/model/plot/arrow.m	(revision 6650)
+++ /issm/trunk/src/m/model/plot/arrow.m	(revision 6650)
@@ -0,0 +1,60 @@
+function arrow(x0,y0,x1,y1,varargin)
+%ARROW - plot arrow, using (x0,y0) and (x1,y1) as initial and end points. options can be specified.
+%
+%   Usage:
+%      arrow(x1,y1,x2,y2,options)
+%      where options is a lit of paired arguments of string OR enums
+%      options can be: 
+%            'ratio': default .5 (ratio headarrow/length)
+%            'widthratio': default is 1/10 of length
+
+
+%recover options
+options=pairoptions(varargin{:});
+ratio=getfieldvalue(options,'ratio',.5);
+widthratio=getfieldvalue(options,'widthratio',.1);
+color=getfieldvalue(options,'color','k');
+
+%compute some values out of (x1,y1) and (x2,y2)
+length=sqrt((x1-x0)^2+(y1-y0)^2);
+width=length*widthratio;
+
+%Build the two points Ap and Bp
+x=zeros(2,1);
+y=zeros(2,1);
+x(1)=x0; y(1)=y0;
+x(2)=x1; y(2)=y1;
+
+Ap=[x(1)
+   y(1)];
+Bp=[x(2)
+   y(2)];
+
+%Build arrowhead first
+ang2=150*2*pi/360;
+rotation=[cos(ang2), sin(ang2); -sin(ang2), cos(ang2)];
+
+E=ratio*rotation*(Bp-Ap)+Bp;
+F=Bp;
+G=ratio*rotation'*(Bp-Ap)+Bp;
+H=Bp/4+E*3/8+G*3/8;
+
+%Build rectangle
+u=Bp-Ap;
+alpha=atan2(u(2),u(1));
+
+A=Ap-[-width/2*sin(alpha)
+   width/2*cos(alpha)];
+ B=H-[-width/2*sin(alpha)
+   width/2*cos(alpha)];
+C=H+[-width/2*sin(alpha)
+   width/2*cos(alpha)];
+D=Ap+[-width/2*sin(alpha)
+   width/2*cos(alpha)];
+
+%Plot arrow
+hold on
+p1=patch([A(1) B(1) C(1) D(1)],[A(2) B(2) C(2) D(2)],color);
+set(p1,'EdgeColor',color); set(p1,'FaceColor',color);
+p2=patch([E(1) F(1) G(1) H(1)],[E(2) F(2) G(2) H(2)],color);
+set(p2,'EdgeColor',color); set(p2,'FaceColor',color);