I nee to write a code to solve a definite integral. The output format has to be fprintf.

%0 to 3 ∫(−x^3 + 3x^2 − 2) dx

syms x

f = -x.^3 + 3.x^2 - 2;

a=0;

b=3;

int(f, a, b);

This is the code i have so far but i keep getting an error. If some one can help me please and thank you. Formatted output must be frprintf.

Answer 1

[Voss]

syms x 
% f = -x.^3 + 3.x^2 - 2;
%              ^ this . should be *
f = -x.^3 + 3*x^2 - 2;
a=0; 
b=3;
output = int(f, a, b)

output = 

fprintf('%f',output)

0.750000

[Aj]

Thank you so much.

[Voss]

You're welcome!

[Jomar]

Sir can you help me to see what is wrong with my code

syms x

y = 0.5*x;

z = int(y, 0, 10);

fprintf('%.2f',z)

it keeps showing error.

[Walter Roberson]

What error message are you observing? Which MATLAB version are you using?

Answer 2

[John D'Errico]

Do you understand that MATLAB REQUIRES a multiplication operator? You cannot just put a number next to a letter, and expect MATLAB to know this is multiplication. So this is not valid code. Did you read the error message? It tells you that.

f = -x.^3 + 3.x^2 - 2;

Fixing that problem, we have

syms x 
f = -x.^3 + 3*x^2 - 2;
a=0; 
b=3;

Next, you need to assign the result of the integration to something.

res = int(f, a, b)

res = 

You now need to turn that symbolic variable into a double.

Dres = double(res)

Dres = 0.7500

Now use fprintf. Read the help for fprintf.