Python for finance

[Not_skilled_at_all]

Hei, after several tries, I haven't managed to find the answer, or run my code.

My problem is to find a specific interest rate for an annual annuity for a period of time.
I tried using a while loop to find alpha and beta interest rates, but my setup is wrong in some way...
Would appreciate all help!

Consider for example an annuity α, which pays $1,000 per year for 25 years, at a cost of $15,000 today. Now consider annuity β, which pays $1,250 per year for 20 years, also at a cost of $15,000 today. Which one is a better investment?
Write a function annuity_rate(n, a, p)
Calculate:
α rate -> annuity_rate(25,1000,15000)
β rate -> annuity_rate(20,1250,15000)

Kind regards
Engineering student

[DeaD_EyE]

Maybe this is interesting for you: https://docs.scipy.org/doc/numpy-1.13.0/...ncial.html

But first you should calculate this on a paper.
Otherwise you're using some functions without knowledge how it's calculated.

[buran]

First step to get help is to post also your code, not just the assignment

[Not_skilled_at_all]

I do understand the finance part of it, and most likely beta is the one with highest interest rate.
But it is the problem of using a while loop to find the interest rate, which is required for this assignment.
In excel this would have been done so much easier.

My code is:

def annuity_rate(n, a, p):
    i = 0.001
    while delta > 0.001:
        calculate_p_annuity = p_annuity(i, n, a)
        RealP = p
        clp = p_annuity(i, 1500, 20)
        delta = calculate_p_annuity - p
        i = i + 0.001
    return

print(annuity_rate(20, 1000, 15000))

[buran]

what is p_annuity?
Also, probably you want your function to return something

[Not_skilled_at_all]

p_annuity is a function that I recall from a previous task, this function calculates and return the present value of an annuity to be received annually for n number of years.

p_annuity (PV) = Annual annuity * (1 - (1 + interest rate)-number of years) / interest rate

[Not_skilled_at_all]

This python forum is completely useless.

[perfringo]

In excel this would have been done so much easier.
This python forum is completely useless.

A bad workman always blames his tools.

[paulyan]

def pv_annuity(rate,n,c):
    pv=c/rate*(1-1/(1+rate)**n)
    return pv
   
def annuity_rate(n,cash, pv):
    i = 0.001
    delta=10000
    while delta > 10:
        pv0 = pv_annuity(i, n,cash)
        delta = abs(pv0- pv)
        i+=0.001
        #print(delta)
    return i

    
#Example
pv_annuity(0.1,20,100)      #Out[890]: 851.3563719758565
annuity_rate(20, 100, 851)  # Out[892]: 0.10000000000000007
annuity_rate(20, 100, 700)  # Out[891]: 0.1300000000000001

[jefsummers]

Look at your code and errors. Insulting is not going to get you help, and we don't do your homework for you.
In the first code you posted,
Line 3 - you reference delta but that variable is not defined at that point. Set it to an arbitrarily large value (1)

Now run it.