DEFINITION MODULE IntElem;

   (* EXPORT QUALIFIED Trapzd, QTrap, QSimp; *)

   FROM NRMath IMPORT RealFunction;

   PROCEDURE Trapzd(    func: RealFunction;
                        a, b: REAL; 
                    VAR s:    REAL; 
                        n:    INTEGER); 
   (*
     This routine computes the n'th stage of refinement of an
     extended trapezoidal rule. The function func is
     to be integrated between limits a and b.  When called
     with n=1, the routine returns the crudest estimate of
     (int (a, b) f(x) dx).  Subsequent calls with n=2,3,... (in that
     sequential order) will improve the accuracy by adding 2^(n-2) 
     additional interior points.
   *)

   PROCEDURE QTrap(    func: RealFunction;
                       a, b: REAL; 
                   VAR s:    REAL); 
   (*
     Returns the integral of the function func from a to b.  
     The parameter eps can be set to the desired fractional accuracy, 
     and jMax so that 2^(jMax-1) is the maximum allowed number of steps.  
     Integration is performed by the trapezoidal rule.
   *)

   PROCEDURE QSimp(    func: RealFunction;
                       a, b: REAL; 
                   VAR s:    REAL); 
   (*
     Returns the integral of the function func from  to b.  
     The parameter eps should be set to the desired fractional accuracy 
     and jMax so that 2^jMax-1 is the maximum allowed number of steps.  
     Integration is performed by Simpson's rule.
   *)

END IntElem.