Looping until threshold is met

I need to create a loop to calculate average temperature using simpsons 1/3rd rule and matlab intergral2 function and determine the minimum number of points (for both x and y values) required for simpsons 1/3rd to acheive an absolute error less the threshold error

Answer 1

[Mathieu NOE]

hello

yes - error is not initialized , and BTW, you are shadowing a native matlab function error , which is not good pratice (could led to conflicts or wrong output)

also , your while loop will never stop because the error is constant !

the output of your function is always 24

you can put a breakpoint where you compute I = h/3*(y(1) +even_sum + odd_sum + y(end));

even though each individual term on the RHS is evolving , the result remains exactly the same.

I checked the code of your 1/3 simpson rule and it's correct IMHO

in other words , you have demonstrated that doing this integral computation with always refined x vector does not change the integral value

[Nilakshi Manawadu]

Thanks Mathieu!

Answer 2

[KALYAN ACHARJYA]

You have to initialize "error" before the loop. The initial value must be less than a threshold value as defined. Also make sure that the error value is continuously increasing as the iteration progress, so that it definitely break loop condition.

[Nilakshi Manawadu]

Thanks Kalyan! I've initalized the error as you've suggested. How would you go about making sure that the error value is continuously increasing as the iteration progress?

[KALYAN ACHARJYA]

Just make sure it will, otherwise, while loop runs continuously. You may check the code with sample 2/3 iteration manually.

error=abs(av_temp_simp13(iter)-av_temp_matlab);