function [c,s,cabs]=formrot(a,b)
    if a== 0
      c=(b==0);
      s=(b ~=0);
      cabs=b;
    elseif b ==0
      c=1;
      s=0;
      cabs=a;
    else
    if abs(a) > abs(b)
      r=b/a;
      factor=sqrt(1+r*r);
      cabs=a*factor;
      c=1/factor;
      s=r*c;
    else
      r=a/b;
      factor=sqrt(1+r*r);
      cabs=b*factor;
      s=1/factor;
      c=r*s;
    end
    end