CODEWITHSUNDEEP
functionrangemax
Ashok
Ashok

Reputation: 214

Python: Maximum of a function in a range

I am trying to find out the maximum value of a function (here it is T(n)) through this code:

for i in range(2, imax-1):
    Q=q(i-1)-q(i)
    Tn=T(i)+(Dt/(rho*cp*0.1))*Q
    y=max(Tn)

But I am getting an error "float' object is not iterable". Any suggestion on this would be helpful to me.

Please note that, "q" and "T(i)" have been defined as functions of "i", and all the other terms are constants.

Upvotes: 0

Views: 2584

Answers (2)

Laurent H.
Laurent H.

Reputation: 6526

The max function returns the maximum values among several ones, so you logically need to pass at least 2 values as parameters, inside a list or a tuple for example.
I suggest you this solution based on your current code to be easily understood: 

y = None
for i in range(2, imax-1):
    Q=q(i-1)-q(i)
    Tn=T(i)+(Dt/(rho*cp*0.1))*Q
    if y is None:
        y=Tn
    else:
        y=max(Tn,y)

To go further (and maybe better), list comprehension is well adapted in this case, as detailed by Andrea in his answer.

Upvotes: 2

Andrea Reina
Andrea Reina

Reputation: 1240

max takes an iterable (e.g. a list, dict, str, etc), so it might look something like, max([1, 2, 3]) #=> 3. A common pattern is to use a comprehension: max(f(x) for x in range(10)). The thing about comprehensions is that they require a single expression, so you can't use the original definition of Tn.

If you expand the definition of Tn so that it's a single expression, we get Tn = T(i) + (Dt/(rho*cp*0.1)) * (q(i-1) - q(1)). Use that in the comprehension and we get max(T(i) + (Dt/(rho*cp*0.1)) * (q(i-1) - q(1)) for i in range(2, imax-1)).

Upvotes: 1

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