# do not understand the integration result

5 views (last 30 days)
cemile basgul on 21 Apr 2020
Commented: cemile basgul on 4 Jun 2020
when I integrate this via: int(1/4624*exp(12028*(2367-t/643*t+2199060)),t,0,360)
I get this result: 1933501^(1/2)*pi^(1/2)*erf((720*1933501^(1/2))/643)*exp(26478763956))/55617472
What does this number mean? why am I getting a value like this?
cemile basgul on 29 Apr 2020
If I use Integral instead of Int, it works, I mean gives a number value such as 3.4059e-09
A=4624;
E=10^5;
R=8.314; %Universal gas constant
Tref=616.15; %Melting point of PEEK in K (343C)
T=T0; %Temperature of constant points
syms t
p=NaN(1,101);
for m=1:101
a(m)=sum(Temperature{m}>=485) ; %constant degree of healing points
b(m)=sum(Temperature{m}<485); %non-isothermal degree of healing points
timea(m)=a(m).*0.003;
timeb(m)=b(m).*0.003;
c(m)=(Temperature{m}(a(m)+1)-Temperature{m}(it(m)))/(time(m)-timea(m)); %slope of the curve
d(m)=Temperature{m}(a(m)+1)-(c(m)*timea(m)); %constant for the linear line equation
F=integral(@(t)(1./(A.*exp((E./R)*((1./(c(m).*t+d(m)))-(1./Tref))))),timea(m),time(m));
p(m)=F^(1/4);
end

Nishant Gupta on 27 May 2020
If you use vpa function for evaluation, the result will be inf since its a very large number.
syms t;
>> expr = 1/4624*exp(12028*(2367-t/643*t+2199060));
>> F = int(expr,[0 360])
F =
(1933501^(1/2)*pi^(1/2)*erf((720*1933501^(1/2))/643)*exp(26478763956))/55617472
>> vpa(F)
ans =
Inf
cemile basgul on 4 Jun 2020
do you know why int and integral gives different results for this? I am not sure which one to use.

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