Writing a long equation in MATLAB

Hi,

I need help writing this equation in MATLAB:

where:

My proposed code is:

d = ((1/(gamma*(abar(t-1,1) - a(t-1,1))))*(1+(a(t-1,1)/(gamma*(abar(t-1,1) - a(t-1,1))))));
GAMMA = gamma*(abar(t-1,1) - a(t-1,1);
exp(-rho*t)*gamma*(abar(t-1,1) - a(t-1,1))*((exp(-(rho+d)*t)/c0)-(exp(-rho*t)/(GAMMA*d))))^(-1);

The code doesn't generate the right numbers though. Is it written correctly?

Thanks!

[David Hill]

Show us your code and ask a specific question. You should also describe or attach your variables and constants.

Answer 1

[Voss]

There are a couple of errors with the parentheses:

d = ((1/(gamma*(abar(t-1,1) - a(t-1,1))))*(1+(a(t-1,1)/(gamma*(abar(t-1,1) - a(t-1,1))))));
GAMMA = gamma*(abar(t-1,1) - a(t-1,1));
%                                    ^ you were missing this parenthesis
c = exp(-rho*t)*gamma*(abar(t-1,1) - a(t-1,1))*((exp(-(rho+d)*t)/c0)-(exp(-rho*t)/(GAMMA*d)))^(-1);
%                                                                                          ^ and you had an extra parenthesis in here

In addition to that, there are some extraneous parentheses that won't affect the result. Removing those, the code looks like this:

d = 1/(gamma*(abar(t-1,1) - a(t-1,1)))*(1+(a(t-1,1)/(gamma*(abar(t-1,1) - a(t-1,1)))));
GAMMA = gamma*(abar(t-1,1) - a(t-1,1));
c = exp(-rho*t)*gamma*(abar(t-1,1) - a(t-1,1))*((exp(-(rho+d)*t)/c0)-exp(-rho*t)/(GAMMA*d))^-1;

In addition to that, you can calculate GAMMA first and use it in the other expressions to shorten them a bit:

GAMMA = gamma*(abar(t-1,1) - a(t-1,1));
d = 1/GAMMA*(1+a(t-1,1)/GAMMA);
c = exp(-rho*t)*GAMMA*((exp(-(rho+d)*t)/c0)-exp(-rho*t)/(GAMMA*d))^-1;

Throughout, I've assigned your last expression to the variable c.

[Walter Roberson]

Yes, I was wondering why they repeat that sub-expression that is the same as Γ

[Selim Elbadri]

Thanks a lot!

[Voss]

You're welcome!