dfdp.m

此为频谱分析工具箱

function y = dfdp(x,f,p,dp,func)
% dfdp : Partials by finite differencies.
%Syntax: df/dp = dfdp(x,y,p,dp,func)
%
% Returns the partial derivatives of function 'func'.
% 'x'(vect) is x axis values, 'y' is y values, 'p' and 'dp' are parameters and
% their variation. 'func' is the function concerned (y=func(x,p)).
% output 'df/dp' is a vector(or matrix) of partials varying of 'dp'.

% Author:  EF <[e-mail]>
% Description: partials computation

% uses : vect2column
% Part of 'Spectral tools'.

x2 = x;

x=vect2column(x);

p0 = p; 		% save init params
y = zeros(length(x), length(p));

for i=1:length(p)
	if (dp(i) == 0)
		dp(i) = 0.00001;
	end;
	p(i) = p(i) + dp(i);
	y(:,i) = (feval(func,x,p)-f)/dp(i);
	p=p0;
end

if (size(x2,1) == 1)
	y = y';
end