How could I check my solution if I am doing a definite integration please?? I mean,since a definite integral is the limit of a sum so could I write a code using sum to check my results??

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Avan Al-Saffar
Avan Al-Saffar 2014-10-27
回答： Torsten 2014-10-27
integral(f(x),a,b)=sum(f(xi),1,N)?

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回答（2 个）

Mischa Kim
Mischa Kim 2014-10-27
Avan, yes you could. For example:
f = @(x) sin(x);
a = 1;
b = 5;
N = 100;
f_int1 = integral(f,a,b)
f_int2 = sum(arrayfun(f,linspace(a,b,N)))*abs(b-a)/N
Try increasing N. Note that you need to sum up small rectangular areas of size f(x)*dx.
Torsten
Torsten 2014-10-27
I guess your question aims at the integration of the expression
f = @(T) ( A*(((N0*sin(omega*T).^2.*(1-2*P(T)./k))+(omega.*cos(omega*T) ) ).^2)./(N0.^2*sin (omega*T).^4.*(P(T)-P(T).^2./k).^2) )
from the other thread you opened.
Did you notice that the denominator of your above expression is zero at T=Pi and f thus becomes infinity at this point ?
Best wishes
Torsten.

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