What's wrong with my code?

here's my code..

syms a
b=2; e=0.9; q=0.4; g=0.6; k=0; d=0.5;
a=1:1:5;

N(a) = (q*b*e/a-d*e)/((q^2)*(e^2)/a+2*e*g)
pi(a)=(b-q*N*e)/a
m=N(a)
n=pi(a)
plot (a,N(a),'b')
hold on 
plot (a, pi(a),'red')

When I run it, it gives me these errors.

Error using  / 
Matrix dimensions must agree.

Error in sev (line 31)
N(a) = (q*b*e/a-d*e)/((q^2)*(e^2)/a+2*e*g)

When I use "./", it plots only pi, but N is on x axis fixed at 0, what can I do to make it work?

Answer 1

[Star Strider]

Try this:

syms a
b=2; e=0.9; q=0.4; g=0.6; k=0; d=0.5;
% a=1:1:5;
N(a) = (q*b*e/a-d*e)/((q^2)*(e^2)/a+2*e*g)
fpi(a)=(b-q*N*e)/a
m=N(a)
n=fpi(a)

figure
fplot (N(a),[1 5],'b')
hold on 
fplot (fpi(a), [1 5],'red')
hold off

.

[Ani Asoyan]

it gives the same error :/

[Ani Asoyan]

Error using  / 
Matrix dimensions must agree.

Error in sev (line 30)
N(a) = (q*b*e/a-d*e)/((q^2)*(e^2)/a+2*e*g)

[Star Strider]

Note : I commented-out this line so that it does not execute:

% a=1:1:5;

So the code I posted with that change runs without error (in R2020a) and produces:

Remove (or comment-out) the ‘a’ assighment as I did, and my code works.

[Ani Asoyan]

Thank you! It worked

[Star Strider]

As always, my pleasure!

Answer 2

[madhan ravi]

Naming a variable pi is a bad idea

doc pi

[Ani Asoyan]

ok but the problem remains

[madhan ravi]

a=1:5 should be after N(a)... and implying ./

[Ani Asoyan]

Thank you! it works