Not enough input arguments error/ int command/ integral calculation

Hi,

I'm trying to calculate very simple integral, and don't understand why I get this error..

Aside from practical help I'd like to understand why this error shows up.

The script is:

integral_1=int(int_1,x1,0,pi/2);
integral_2=int(int_2,x2,0,3);

function f1=int_1(x1)
f1=8+4.*cos(x1);
end

function f2=int_2(x2)
f2=1-exp(-x2);
end

Answer 1

[Bora Eryilmaz]

Use the integral command, not int. The integral command does numerical integration. The int command is for symbolic integration. Also use "@" in front of the function names to pass their function handles to the integral function.

integral_1=integral(@int_1,0,pi/2)

integral_1 = 16.5664

integral_2=integral(@int_2,0,3)

integral_2 = 2.0498

function f1 = int_1(x1)
  f1 = 8+4.*cos(x1);
end

function f2 = int_2(x2)
  f2 = 1-exp(-x2);
end

[Efrat Hazan Elimelech]

Thanks!

Answer 2

[Cris LaPierre]

int is for symbolic integration. See Bora's answer if you want to perform numerical integration.

The error is because of how you have defined your integration functions. The integration function can't have inputs. It is probably easier if you define your functions as symbolic functions. You also need to declare your integrabtion variables as symbolic.

syms x1 x2
int_1(x1) = 8+4.*cos(x1);
int_2(x2) = 1-exp(-x2);

integral_1=int(int_1,x1,0,pi/2)

integral_1 = 

integral_2=int(int_2,x2,0,3)

integral_2 = 

[Efrat Hazan Elimelech]

OK Thank you!