functions in cheby.i -

             cheby_deriv(fit)  
 
    returns Chebyshev fit to the derivative of the function of the  
    input Chebyshev FIT.  
    

             cheby_eval(fit, x)  
 
    evaluates the Chebyshev fit (from cheby_fit) at points X.  
    the return values have the same dimensions as X.  
    

             fit = cheby_fit(f, interval, n)  
         or fit = cheby_fit(f, x, n)  
 
    returns the Chebyshev fit (for use in cheby_eval) of degree N  
    to the function F on the INTERVAL (a 2 element array [a,b]).  
    In the second form, F and X are arrays; the function to be  
    fit is the piecewise linear function of xp interp(f,x,xp), and  
    the interval of the fit is [min(x),max(x)].  
    
    The return value is the array [a,b, c0,c1,c2,...cN] where [a,b]  
    is the interval over which the fit applies, and the ci are the  
    Chebyshev coefficients.  It may be useful to use a relatively  
    large value of N in the call to cheby_fit, then to truncate the  
    resulting fit to fit(1:3+m) before calling cheby_eval.  
    

             cheby_integ(fit)  
         or cheby_integ(fit, x0)  
 
    returns Chebyshev fit to the integral of the function of the  
    input Chebyshev FIT.  If X0 is given, the returned integral will  
    be zero at X0 (which should be inside the fit interval fit(1:2)),  
    otherwise the integral will be zero at x=fit(1).  
    

             cheby_poly(fit)  
 
    returns coefficients An of x^n as [A0, A1, A2, ..., An] for  
    the given FIT returned by cheby_fit.  You should only consider  
    actually using these for very low degree polynomials; cheby_eval  
    is nearly always a superior way to evaluate the polynomial.