http://mail.python.org/pipermail/tutor/2005-January/034696.html
Read the whole thread for other ideas.
Kent
Jacob S. wrote:
Hi all.
Long time no see. (About five days, right?)
Anyway, I know the first thing that some of you are going to say is using eval(). I don't want a whole
guilt trip on security risks and all that. I do not want to share the code with anyone else while it's on my
computer, and I sure don't have anyone near me that knows python. I would be surprised if more than 50
people in Portland, IN knew anything about python. So security is not a problem. I guess what I'm
looking for is someone who knows the Reimann Sum better than I do and can tell me whether I can do
something to make it more efficient. It's horribly slow with ten thousand steps-- I don't know the notation
very well, but it loops the loop O(step*(maximum-minimum)) times, which is horribly sucky.
In case anyone doesn't know, Reimann's sum is the computer's version of the definite integral, the area
under a curve in a particular domain.
Basic input and output.
If a curve is a straight line, say y = x, the area under the line on an interval can be found by geometric means.
However, if you use a parabola, or any other function, say y = 3*x**2,
What is the function? 3*x*x What is the minimum? 2 What is the maximum? 5 117.000435
Which, considering that it is supposed to be exactly 117, It's darn good. Unfortunately, it also takes about
10 seconds to do all that.
Any suggestions? Any advice? TIA
Jacob Schmidt
############################ from __future__ import division import psyco psyco.full() fofx = raw_input("What is the function? ") minimum = raw_input("What is the minimum? ") maximum = raw_input("What is the maximum? ") minimum = float(minimum) maximum = float(maximum) total = 0 step = 100000 x = minimum while minimum <= x <= maximum: area = eval(fofx)*1/step total = total+area x = x+1/step print total ############################# _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
_______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
