Re: calculating the area of a circle with bc
- From: Karl Larsen <klarsen1@xxxxxxxxx>
- Date: Sun, 28 Mar 2010 14:03:09 -0600
On 03/28/2010 01:51 PM, Tony Arnold wrote:
Rei Shinozuka wrote:
The area is proportional to the square of the diameter or radius.I stand corrected again. And I thought I was good at maths!
Data form www.dominos.com:
Domino's 10" pizza is $7.00
Domino's 14" pizza is $11.99.
The 10" price/diameter is 70 "cents per inch."
The 14" price/diameter is 85 "cents per inch."
implying that the 10" is a better buy.
But price/area shows:
The 10" price/area is 8.6 cents per square inch.
The 14" price/area is 7.7 cents per square inch.
The 14" pizza is 10% cheaper than the 10" pizza.
For a pure comparisons, you are correct: coefficients like pi are not
needed to compare. But you need to square the linear size of the pizza.
On 03/28/2010 03:24 PM, Tony Arnold wrote:The area of a circle comes from pi r squared = pi (d/2) squared. How you do this with bc is not known to me but the formula is above and I can prove it.
Since the area of a pizza is directly proportional to its diameter, you
only really need to calculate the price/diameter to find out the best
value for money!
Jozsef Vadkan wrote:
sh count.sh 0.45 2200
0.45 => diameter [in meter]
2200 => e.g. xy money
$(echo "scale=100; 2^($1/2) * $(echo "scale=100; 4*a(1)" | bc -l)" | bc
-l) => area of the circle
xy money => some nations currency
i'm dividing the area of the circle because i want to get the "xy
echo "$2/$(echo "scale=100; 2^($1/2) * $(echo "scale=100; 4*a(1)" | bc
-l)" | bc -l)" | bc -l
is there a shorter/better way?
it would be a pizza price calculator. [:D]
45 cm pizza = 2200 xy money
30 cm pizza = 1260 xy money
22 cm pizza = 960 xy money
i just want to count that, what will i have to choose to get the best
price for "xy money/square meter" pizza.
don't laugh. [:D]
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