Calculate the derivative of a segment function

a = 0.6;

b = 0.1;

x = linspace(0,3*a,181);

% Here is my segment function

% How can i calculate its derivative

function [yu] = up(x1,a,b)

yu = zeros(size(x1));

for k = 1 : length(yu)

x = x1(k);

if x > 0 && x <= a;

% x is in the range [0, a]

yu(k) = (b^2 - ((b^2)/(a^2)).*(x-a).^2).^(1/2);

else x > a && x < 3*a;

% x is in the range [a, 3*a]

yu(k) = (((b/(4*a^3)).*x.^(3)) - ((3*b)/(2*a^2)).*(x.^2) + (9*b)/(4*a).*x);

end

end

end

[KSSV]

DErivative wrt what?

Answer 1

[VBBV]

a = 0.6;
b = 0.1;  
x = linspace(0,3*a,181);
Y = up(x,a,b); % 
plot(x,Y)

% Here is my segment function
% How can i calculate its derivative  
function [yu] = up(x1,a,b)
yu = zeros(size(x1));
    for k = 1 : length(yu)
        x(k) = x1(k);
        if x(k) > 0 && x(k) <= a;
            % x is in the range [0, a]
            yu(k) = (b^2 - ((b^2)/(a^2)).*(x(k)-a).^2).^(1/2); 
        else x(k) > a && x(k) < 3*a;
            % x is in the range [a, 3*a]
            yu(k) = (((b/(4*a^3)).*x(k)^(3)) - ((3*b)/(2*a^2)).*(x(k)^2) + (9*b)/(4*a)*x(k));
        end
    end
yu = gradient(yu)./gradient(x); % derivative using gradient  
end

you can use diff as well to check the derivative property

[Xuejian Niu]

ty so much, smart way~

[VBBV]

If it solved your problem, pls accept the answer:) thanks