## functions in cheby.i - c

cheby_deriv

cheby_deriv(fit) returns Chebyshev fit to the derivative of the function of the input Chebyshev FIT. Interpreted function, defined at i/cheby.i line 76SEE ALSO: cheby_fit, cheby_integ

cheby_eval

cheby_eval(fit, x) evaluates the Chebyshev fit (from cheby_fit) at points X. the return values have the same dimensions as X. Interpreted function, defined at i/cheby.i line 36SEE ALSO: cheby_fit

cheby_fit

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. Interpreted function, defined at i/cheby.i line 7SEE ALSO: cheby_eval, cheby_integ, cheby_deriv

cheby_integ

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). Interpreted function, defined at i/cheby.i line 54SEE ALSO: cheby_fit, cheby_deriv