/*******************************************************************
 *  Making spin-plot varing the coefficient for variable x1 only   *
********************************************************************/
%macro sp_plotbx1(outfile="c:\sp_plotbx1.gif", data=_spinplt ,
                x1lo=-10, x1hi=10, x1by=1, x2lo=-10, x2hi=10, x2by=1,
	            cons=0, bx1=0, bx2=0, bx1x2=0,bx1x1=0, bx2x2=0, bx1x1x2=0, bx1x2x2=0, 
                title=Spin Plot, title2=' ',
                plot=, gopt=, angle=100, slen=6, bx1_lo=-5, bx1_hi=5, bx1_by=1, cmd=plot); 

  * reset graph settings ;
  goptions reset=all;

  filename out clear ;
  filename out &outfile ;

  /* assign graphics options for the animation */
 
  goptions gsfname=out dev=gifanim gcopies=0 iteration=0 delay=50 &gopt;

  %let bx1_lo_ = %sysevalf(&bx1_lo*100);
  %let bx1_hi_ = %sysevalf(&bx1_hi*100);
  %let bx1_by_ = %sysevalf(&bx1_by*100);

  * make graph going forward from bx1lo to bx1hi ;
  %do bx1_ = &bx1_lo_ %to &bx1_hi_ %by &bx1_by_ ;
    %let bx1 = %sysevalf(&bx1_ / 100);
 
    %if &bx1_ =  &bx1_lo_ %then %do; goptions gsfmode=replace; %end;
    %if &bx1_ >  &bx1_lo_ %then %do; goptions gsfmode=append; %end;
    /* %if &bx1_ >= &bx1_hi_ %then %do; goptions gepilog='3B'x; %end; */

  %local bstring;
  %fixlen(&bx1, &slen);
  %let title =&title;
  %let title2=%str(y=&cons)%str(&bstring)%str(*x1+&bx2*x2+&bx1x2*x1*x2+&bx1x1*x1x1+&bx2x2+x2x2&bx1x1x2*x1x1x2+&bx1x2x2*x1x2x2);

    %sp_plot( angle=&angle,data=&data ,
              x1lo=&x1lo, x1hi=&x1hi, x1by=&x1by, x2lo=&x2lo, x2hi=&x2hi, x2by=&x2by,
	          cons=&cons, bx1=&bx1, bx2=&bx2, bx1x2=&bx1x2,bx1x1=&bx1x1, 
              bx2x2=&bx2x2, bx1x1x2=&bx1x1x2, bx1x2x2=&bx1x2x2, 
              title=&title, title2=&title2,plot=&plot,gopt=&gopt,cmd=&cmd, reset=no); 
  %end;

  * make graph going backward from bx1hi to bx1lo ;
  %do bx1_ = &bx1_hi_ %to &bx1_lo_ %by -&bx1_by_ ;
    %let bx1 = %sysevalf(&bx1_ / 100);

    %if &bx1_ >  &bx1_lo_ %then %do; goptions gsfmode=append; %end;  
    %if &bx1_ <= &bx1_lo_ %then %do; goptions gepilog='3B'x; %end;

  %local bstring;
  %fixlen(&bx1, &slen);
  %let title =&title;
  %let title2=%str(y=&cons)%str(&bstring)%str(*x1+&bx2*x2+&bx1x2*x1*x2+&bx1x1*x1x1+&bx2x2+x2x2&bx1x1x2*x1x1x2+&bx1x2x2*x1x2x2);

  %sp_plot( angle=&angle, data=&data ,
            x1lo=&x1lo, x1hi=&x1hi, x1by=&x1by, x2lo=&x2lo, x2hi=&x2hi, x2by=&x2by,
            cons=&cons, bx1=&bx1, bx2=&bx2, bx1x2=&bx1x2, bx1x1=&bx1x1, 
            bx2x2=&bx2x2, bx1x1x2=&bx1x1x2, bx1x2x2=&bx1x2x2, 
            title=&title, title2=&title2, plot=&plot, gopt=&gopt,cmd=&cmd, reset=no); 
  %end;

  filename out clear ;
  goptions reset=all;
%mend sp_plotbx1;