How do I get it to recognise I?

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Im trying to format the output for this calculation but it keeps giving my an error for the line where Im formatting i saying i is undefined, Im guessing its something to do with i being used in the definition but Im not entirely sure and also not sure how to get it to recognize it.

There could be a problem with my n, Im trying to get it to double each time in the range to 512 so not sure if thats the problem but Im also working on trying to figure that out and not sure if thats affecting i

What I have tried:

Theres some more code before this just getting input and defining more definitions but I dont think its relevant to the problem.

Python

def my_trap(a,b,n):
    sum= 0
    h= (b-a)/n #width of each interval
    for i in range(1,n+1):
        x=a+i*h
        sum=sum+2*f(x)
        return (h/2)*(sum+f(a)+f(b))
   
print('\nThis programme estimates the integral of the function sin(x) in the \
          integral [a,b] using the trapezoidal method.')

a=getinput('a')
b=getinput('b')

n=512/2
n=n*2

error= analytical(a,b)-my_trap(a,b,n)

print('{0:<20}'.format(i),'|'\
      '{0:<20.5f}'.format(my_trap(a,b,n)), '|', \
      '{0:<20.5f}'.format(error))

Posted 26-Mar-20 13:27pm

CiaraMc96

Updated 26-Mar-20 13:33pm

phil.o

v3

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Comments

Richard MacCutchan 27-Mar-20 4:29am

The return statement in my_trap is wrongly indented.

CiaraMc96 27-Mar-20 6:57am

Thank you, fixed that now but it still isnt recognizing i, how do I make it accessible elsewhere with what phil said?

phil.o 27-Mar-20 10:06am

i being only accessible and assigned inside the loop, you have to create another variable in the scope you wish to use it. Then, in the loop, assign the value of i to that broader variable. BUT: you will only be able to get the last value of i, unless you have a mechanism to exit the loop early. If you don't exit the loop early, then you can assume the last value of i will always be n.

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phil.o · Answer 1 · 2020-03-26T13:32:00

Variable i is scoped to the for loop; this means that you can only use it inside the loop, and it will be unaccessible from anywhere else.

Please always enclose your code block between <pre> tags; especially for python, where indentation is of utmost importance, we need to have the exact indentation of the code.