Why does this function handle not take the inputs?

Question

0 个投票

So I have to approximate the value of sin(x) using the Runge-Kutta method. Here's my code:

function [X,Y]=rungekutta(fprime, timespan, y0, h) 
if ~exist('h','var') 
h=.1;
end
Y(1)=y0;
X(1)=timespan(1);
i=2;
while X(end)<timespan(end)
  X(i)=X(i-1) + h;
  k1 = h*fprime(X(i-1),Y(i-1));  
  k2 = h*fprime(X(i-1+h/2),Y(i-1)+k1/2);     
  k3 = h*fprime(X(i-1+h/2),Y(i-1)+k2/2);     
  k4 = h*fprime(X(i-1+h),Y(i-1)+k3);         
  Y(i) = Y(i-1) + (k1+2*k2+2*k3+k4)*h/6; % Approx soln
  i=i+1;
end
X=X';
Y=Y';
abs_err=mean(abs(Y-sin(X)));
plot(X,Y);
xlabel('Time(seconds)'); ylabel('Function Y');
title('Runge-Kutta Method');
hold on
plot(X,sin(X));
legend('Approximation','sin(x)');
display=fprintf('The absolute error is %f',abs_err);

When I type in the command window [X,Y]=rungekutta(@(X,Y)(cos(X,Y)), [0 10], sin(0), .5) using the my desired parameters, it gives me an error with cos saying "too many input arguments". Is this because I created the function handle within the input?