iterations / trial and error method to find a variable.

I have this enthalpy equation where all the variables are known but the temperature T2. I want to write a code to find the best possible solution for T2 by iteration / trial and error method. you can start from T2= 400 for instance.

 deltah=a(T2-T1)+(b/3)*(T2^2-T1^2)+(c/3)*(T2^3-T1^3)+(d/4)*(T2^4-T1^4)

 a=28.9; b=0.1967*10^-2; c=0.4802*10^-5; d=-1.966*10^-9; dltH=8900; T2=400; T1=300;

Answer 1

[Jan]

You can use fzero to solve this 3rd order polynomial.

[dpb]

which would look like

>> fndH=@(T2) a*(T2-T1)+(b/3)*(T2^2-T1^2)+(c/3)*(T2^3-T1^3)+(d/4)*(T2^4-T1^4)-dltH
fndH =
function_handle with value:
  @(T2)a*(T2-T1)+(b/3)*(T2^2-T1^2)+(c/3)*(T2^3-T1^3)+(d/4)*(T2^4-T1^4)-dltH
>> fzero(fndH,T2)
ans =
593.8714
>> fndH(ans)
ans =
   0
>>

[Tarek Chaabo]

thank you so much i learned something new. Is there another way where i can see each value of T2 printed to the command window until the final value of 593.8714 ??

[dpb]

Read the documentation; specifically look at the additional, optional input argument list...