[Tutor] I need help with Python

[Jeff Shannon]

Vickram wrote:

> I need to make calculations using very large numbers, unfortunately, i 
> am getting a "ZeroDivisionError: float division" error.

This would be easier to determine if you had included the rest of the 
traceback, which would tell us exactly *where* the error is.  But 
let's see what we can do.

The error means that you're dividing by zero.  Mathematics tells us 
that this yields an undefined result, but computers can't handle 
undefined numbers, so it's not allowed and is considered an error. 
The trick is to find out where in your program you might be dividing 
by zero.

> import cmath
> 
> a = 186282.397
> b = 1609.344
> c = 365.2421987817
> d = 99.9999999999999999995
> e = (d*a)/100
> beta = ((e*b)**2) / ((a*b)**2)
> gamma = 1/math.sqrt(1-beta)

All of this should be good.  You've got a set of floating point 
numbers, none of which approximate zero all that closely.

> ty = 100000
> td = ty*c
> print
> print "speed of light =",a,"mps"
> print "1 mile =",b,"metres"
> print "1 year =",c,"days"
> print
> print "% of c =",d,"%"
> print "gamma =",gamma
> print
> print "normal time = ",ty,"years"
> print " ",td,"days"
> print
> print "time dilation =",ty/round(gamma),"yrs"

Here's where I think your problem is.  You're rounding gamma to the 
nearest integer, and then dividing by it.  You previously defined 
gamma as a fraction -- it's somewhere between 0 and 1.  If gamma 
happens to be closer to 0, then round(gamma) will be equal to 0, and 
there you've got an illegal division by zero.

I'm not sure why you'd want to round off gamma for this calculation, 
anyhow.  Perhaps you meant to round off the results of ty/gamma, instead?

Jeff Shannon
Technician/Programmer
Credit International