Putting user input values outside function and having ode45 incorporate them in equations?

% code
g=9.8;
%Mass 1 
promptm1='Enter a value for mass 1(between 1 and 4) ';
m1=input(promptm1);
while (m1<=0)||(m1>=5)
disp('Input is outside specified range. Try again.')
promptm1='Enter a value for mass 1(between 1 and 4) ';
m1=input(promptm1);
 if (m1>0)&&(m1<5)
    fprintf('Mass 1 will be: %2.0f \n',m1)
 end
end
%Mass 2
promptm2='Enter a value for mass 2(between 1 and 4) ';
m2=input(promptm2);
while (m2<=0)||(m2>=5)
disp('Input is outside specified range. Try again. ')
promptm2='Enter a value for mass 2(between 1 and 4) ';
m2=input(promptm2);
 if (m2>0)&&(m2<5)
    fprintf('Mass 2 will be: %2.0f \n',m2)
 end
end
%Length 1
promptl1='Enter a value for length 1(between 1 and 4) ';
L1=input(promptl1);
while (L1<=0)||(L1>=5)
disp('Input is outside specified range. Try again.')
promptl1='Enter a value for mass 1(between 1 and 4) ';
L1=input(promptl1);
 if (L1>0)&&(L1<5)
    fprintf('Length 1 will be: %2.0f \n',L1)
 end
end
%Length 2
promptl2='Enter a value for length 2(between 1 and 4) ';
L2=input(promptl2);
while (L2<=0)||(L2>=5)
disp('Input is outside specified range. Try again.')
promptl2='Enter a value for length 2(between 1 and 4 )';
L2=input(promptl2);
 if (L2>0)&&(L2<5)
    fprintf('Length 2 will be: %2.0f \n',L2)
 end
end
%Time
prompt= 'Enter how long you would like the double pendulum to swing (in seconds)';
T=input(prompt);
y0=[pi/2 0 pi 0];
%%Double Pendulum Equations
[t,y]=ode45(@pend, [0 T], y0);
end

This is the funtion file (pend.m)

    % code
function [yprime] = pend(t, y)
g=9.8;
yprime=zeros(4,1);
a = (m1+m2)*l1 ;
b = m2*l2*cos(y(1)-y(3)) ;
c = m2*l1*cos(y(1)-y(3)) ;
d = m2*l2 ;
e = -m2*l2*y(4)* y(4)*sin(y(1)-y(3))-g*(m1+m2)*sin(y(1)) ;
f = m2*l1*y(2)*y(2)*sin(y(1)-y(3))-m2*g*sin(y(3)) ;
yprime(1) = y(2);
yprime(3)= y(4) ;
yprime(2)= (e*d-b*f)/(a*d-c*b) ;
yprime(4)= (a*f-c*e)/(a*d-c*b) ;
yprime=yprime';
end
  end

I cant figure out how to make the m1,m2,l1,l2 inside the function equal the m1,m2,l1,l2 defined user inout variables outside the function. Please help asap

Answer 1

[Walter Roberson]

You can use shared variables, or you can parameterize your function