Error RungeKutta method......not enough input arguments

3 次查看（过去 30 天）
Camilo Sánchez
Camilo Sánchez 2017-11-10
评论： Camilo Sánchez 2017-11-10
function [xSol,ySol] = runKut4(dEqs,x,y,xStop,h)
%function [xSol,ySol] = runKut4(dEqs,x,y,xStop,h)
% 4th-order Runge--Kutta integration.
% USAGE: [xSol,ySol] = runKut4(dEqs,x,y,xStop,h)
% INPUT:
% dEqs = handle of function that specifies the 1st-order differential equations
% F(x,y) = [dy1/dx dy2/dx dy3/dx ...].
% x,y = initial values; y must be row vector.
% xStop = terminal value of x.
% h = increment of x used in integration.
% OUTPUT:
% xSol = x-values at which solution is computed.
% ySol = values of y corresponding to the x-values.
if size(y,1) > 1;
y = y';
end % y must be row vector
xSol = zeros(2,1);
ySol = zeros(2,length(y));
xSol(1)= x;
ySol(1,:)=y;
i = 1;
while x < xStop
i = i + 1;
h = min(h,xStop - x);
K1 = h*feval(dEqs,x,y);
K2 = h*feval(dEqs,x + h/2,y + K1/2);
K3 = h*feval(dEqs,x + h/2,y + K2/2);
K4 = h*feval(dEqs,x+h,y + K3);
y = y + (K1 + 2*K2 + 2*K3 + K4)/6;
x = x + h;
xSol(i) = x;
ySol(i,:) = y; % Store current soln.
end
-------------------------------------------------------------------------
function F = fex7_4(x,y)
% Differential. eqs. used in Example 7.4
F = zeros(1,2);
F(1) = y(2); F(2) = -0.1*y(2) - x;
[x,y] = runKut4(@fex7_4,0,[0 1],2,0.25);
printSol(x,y,1)
--------------------------------------------------------------
>> fex7_4 Error using fex7_4 (line 4) Not enough input arguments.
not enough input arguments ??????
  3 个评论
显示 1更早的评论
Camilo Sánchez
Camilo Sánchez 2017-11-10
Upss sorry....here is:
[x,y] = runKut4(@fex7_4,0,[0 1],2,0.25);
printSol(x,y,1)
Camilo Sánchez
Camilo Sánchez 2017-11-10
>> fex7_4 Error using fex7_4 (line 5) Not enough input arguments.

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Mischa Kim
Mischa Kim 2017-11-10
编辑：Mischa Kim 2017-11-10
Store runKut4 and fex7_4 in separate m-files and then execute
[x,y] = runKut4(@fex7_4,0,[0 1],2,0.25);
e.g. in the MATLAB command window and you should get results for x and y. printSol is probably another function you have access to, I do not know. But you could simply use plot to plot the solution trajectory.

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Numerical Integration and Differential Equations 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by