facing problem to function calling

suketu vaidya

2020 11 9

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更新时间：2021 8 20

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function [x,y1]=exlicit(f1)
    h =1;
x = -pi:h:pi;
n = 0:1:10;
y1 = [0];
for   i=1:n
x(i+1)=x(i)+h;
y1(i+1)=y1(i)+h*f1(x(i),y1(i)); 
end
end
%heun's method
function [x,y1]=heun(f1)
    h =1;
x = -pi:h:pi;
n = 0:1:10;
y1 = [0];
for i=1:n
x(i+1)=x(i)+h;
ynew=y1(i)+h*(f1(x(i),y1(i)));
y1(i+1)=y1(i)+(h/2)*(f1(x(i+1),y1(i))+h*f1(x(i+1),ynew));
end
end
%euler implicit method
function [x,y1]=implicit(f1)
    h =1;
x = -pi:h:pi;
n = 0:1:10;
y1 = [0];
for i=1:n
x(i+1)=x(i)+h;
ynew=y1(i)+h*(f1(x(i),y1(i)));
y1(i+1)=y1(i)+h*f1(x(i+1),ynew);
end
end
%Runge Kutta 4th order  method:
function [x,y1]=Runge(f1)
h =1;
x = -pi:h:pi;
n = 0:1:10;
y1 = [0];
for i=1:n
k1=f1(x(i),y1(i));
y1(i+1)=y1(i)+(h*k1)
end
end
 function dy =f1(x,y1)
d=50;
c1=-1-d^2/(d^2+1);
x=0:0.01:10;
dy=c1*exp(-d*x)+d*sin(x)/(d^2+1)+d^2*cos(x)/(d^2+1); 
 end
 %plot 
%call function 
[x2,y2]=exlicit(f1);
[x3,y3]=heun(f1);
[x4,y4]=implicit(f1);
[x5,y5]=Runge(f1);
plot(x2,y2,'g-',x3,y3,'b',x4,y4,'m-',x5,y5,'r')
hold on
end

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suketu vaidya 2020-11-9

yes sir ,

Plot numerical solutions of the problem obtained with explicit Euler, implicit Euler, Heun and RK4 methods. Plot all numerical solutions on a single figure together with analytical one

Rik 2020-11-9

Well, you will first have to fix what is inside a function and what is outside of it. Pay attention to m-lint: those squiggly lines under your code should all be gone. It will give you advice how to solve them.

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