functions in zroots.i -

             laguerre(a,x)  
 
     Given the coefficients a(1:m+1) of the m'th degree  
     complex polynomial Sum(a(i)*x^(i-1)) and a guess x, returns a root.  
     See Numerical Recipes (Press, et. al., Cambridge Univ. Press 1988),  
     section 9.5.  

             zroots(a)  
 
     returns the vector of (complex) roots of the (complex)   
     polynomial: Sum(a(i)*x^(i-1)) using Laguerre's method.  
     The roots are sorted in order of increasing real parts.  Call with  
     non-zero imsort keyword to sort into increasing imaginary parts.  
     See Numerical Recipes (Press, et. al., Cambridge Univ. Press 1988),  
     section 9.5.