I keep getting errors when trying to use the ode 45 function to integrate an acceleration equation to determine vO vs. t, transferring all constants to the function using global variables.
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This is my main code:
clc
clear
f=3500;
cd=.6;
cf=3;
m0=600;
c=2;
d=0;
dN=0;
for t=0:0.1:5
vE=0;
m=m0-(c*t);
n=0;
v=0;
a=(f/m)-((cd/m)*v);
vE=vE+(a*.1);
fprintf('VEuler is %1.2f when t is %1.1f \n',vE,t)
vO=v+vE;
dN=((5+t)*((vO+vE)/2))+d;
end
fprintf('After initiating acceleration, the dragster has moved %1.2f meters\n',dN)
y0 = 0;
tspan=0:0.1:5;
[t,y]= ode45('fun',tspan,y0);
fprintf('\n t y\n');
tvalues=transpose(t);
fxvalues=transpose(fx);
With the function:
function fx=fun(t,y0)
global f cd cf m0 c;
fx=(((cf/m0-c.*t))*y0)-((cd/m0-c.*t).*y0.^2)+(f/m0-c.*t);
end
Matlab is telling me that it's returning a vector length of zero, an ode arguements error (odearguments(FcnHandlesUsed, solver_name, ode, tspan, y0, options,varargin);)
and that there's an error in the ode function itself. I've explored the internet and tried several online solutions but none have worked.
1 个评论
madhan ravi
2018-11-30
编辑：madhan ravi
2018-11-30
please don't close the question that have an answer , thank you for understanding , see https://www.mathworks.com/help/matlab/math/parameterizing-functions.html , what's unclear?
采纳的回答
madhan ravi
2018-11-30
编辑：madhan ravi
2018-11-30
clc
clear
f=3500;
cd=.6;
cf=3;
m0=600;
c=2;
d=0;
dN=0;
for t=0:0.1:5
vE=0;
m=m0-(c*t);
n=0;
v=0;
a=(f/m)-((cd/m)*v);
vE=vE+(a*.1);
fprintf('VEuler is %1.2f when t is %1.1f \n',vE,t)
vO=v+vE;
dN=((5+t)*((vO+vE)/2))+d;
end
fprintf('After initiating acceleration, the dragster has moved %1.2f meters\n',dN)
y0 = 0;
tspan=0:0.1:5;
[t,y]= ode45(@(t,y0)fun(t,y0,f, cd ,cf, m0, c),tspan,y0);
fprintf('\n t=%f y=%f\n',t,y);
tvalues=transpose(t);
fxvalues=transpose(y); % what's fx? should be y because it's the solution which is returned from ode45
function fx=fun(t,y0,f, cd ,cf, m0, c)
fx=(((cf/m0-c.*t))*y0)-((cd/m0-c.*t).*y0.^2)+(f/m0-c.*t);
end
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