[英]How do I return a value within a while loop
I'm working on an assignment for one of my CS courses. 我正在为我的其中一门CS课程分配作业。 I've gotten this thing just about figured out, but I don't know how to return a value within my while loop.
我已经弄清楚了这件事,但是我不知道如何在我的while循环中返回值。
The problem I'm having is I need to add the quotient each time through the while loop until t == 0. I have everything working correct until I get to the addition of the division, all it is adding together the same two number. 我遇到的问题是,我每次都要通过while循环将商相加,直到t ==0。在使除法相加之前,所有工作都是正确的,所有的都将相同的两个数相加。 What I need it to do is remember what "division" was equal to the previous term through the loop then add it to what the current loop calculates.
我需要做的是记住整个循环中“除法”等于前一项,然后将其添加到当前循环的计算中。
I hope that made any semblance of sense. 我希望这看起来很合理。 Here is a link to the question for those of you who now have a headache after reading my question
这是针对您阅读我的问题后现在头疼的那些人的问题的链接
# FORMULA IS AS FOLLOWS
# 1 + x + (x^t)/(t!) until t == 1
t = int(input("Enter a non negative integer for t: "))
x = float(input("Enter a real number for x: "))
fact = 1
finalProduct = 1
counter = 1
while counter <= t :
counter = counter + 1
fact = fact * counter
print("counter:",counter)
print("fact:",fact)
xPwr = (x**counter)
division = (xPwr / fact)
print("Division: ",division)
addition = (division + division)#HERE IS MY PROBLEM
print("Sum:", addition)
finalProduct = (1 + x + addition)
print("finalProduct",finalProduct)
This follows very closely to the problem description given by your instructor: 这与您的老师给出的问题描述非常接近:
x = float(input("Enter a real number for x: "))
t = int(input("Enter a non negative integer for t: "))
counter = 1
series = 1
num = 1
denom = 1
while counter <= t :
num = num * x
denom = denom * counter
series = series + num / denom
counter = counter + 1
print(series)
Here is an example: 这是一个例子:
Enter a real number for x: 2.0
Enter a non negative integer for t: 3
6.333333333333333
Here is a slightly extended version. 这是一个稍微扩展的版本。
First, you should realize that the given series is an approximation of e ** x
; 首先,您应该意识到给定的级数是
e ** x
的近似值; the more terms are included, the more accurate the final result. 包含的术语越多,最终结果越准确。 Let's explore that:
让我们探索一下:
import math
def approx_ex(x, max_t):
"""
Maclaurin series expansion for e**x
"""
num = 1 # == x**0
denom = 1 # == 0!
total = 1.0 # term_0 == (x**0) / 0!
for t in range(1, max_t + 1):
# modify numerator and denominator to find next term
num *= x # x**(t-1) * x == x**t
denom *= t # (t-1)! * t == t!
# keep a running total
total += num / denom
return total
def main():
x = float(input("Input a real number: "))
actual = math.e ** x
print("\nApproximation of e ** {} == {}\n".format(x, actual))
for terms in range(1, 16):
approx = approx_ex(x, terms)
error = approx - actual
print("{:>2d}: {:16.12f} ({:16.12f})".format(terms, approx, error))
if __name__ == "__main__":
main()
This runs like 这就像
Input a real number: 3.205
Approximation of e ** 3.205 == 24.655500016456244
1: 4.205000000000 (-20.450500016456)
2: 9.341012500000 (-15.314487516456)
3: 14.827985854167 ( -9.827514162290)
4: 19.224423254193 ( -5.431076762264)
5: 22.042539627609 ( -2.612960388847)
6: 23.547883457076 ( -1.107616559380)
7: 24.237115881853 ( -0.418384134603)
8: 24.513239622030 ( -0.142260394426)
9: 24.611570353948 ( -0.043929662508)
10: 24.643085353528 ( -0.012414662928)
11: 24.652267678406 ( -0.003232338051)
12: 24.654720124342 ( -0.000779892115)
13: 24.655324746590 ( -0.000175269866)
14: 24.655463161897 ( -0.000036854559)
15: 24.655492736635 ( -0.000007279822)
which very clearly shows how the result gets better and better as more terms are summed together. 这非常清楚地表明,将更多的术语加在一起,结果会越来越好。
You should use Recursive Functions for passing a variable to next loop. 您应该使用递归函数将变量传递到下一个循环。
def factorial(n):
if n == 1:
return 1
else:
return n * factorial(n-1)
It is passing "n-1" value to next loop. 它将“ n-1”值传递给下一个循环。
You want to assign the return value of core back to the local y variable, it's not passed by reference: 您想将core的返回值分配回本地y变量,它不会通过引用传递:
y = core(x) You'll also need to set y before you go into the loop. y = core(x)在进入循环之前,您还需要设置y。 Local variables in functions are not available in other functions.
函数中的局部变量在其他函数中不可用。
As a result, you don't need to pass y to core(x) at all: 结果,您根本不需要将y传递给core(x):
def core(x):
y = input("choose a number: ")
if y == x:
print("You gussed the right number!")
return y
elif y > x:
print("The number is lower, try again")
return y
else:
print("The number is higher, try again")
return y
and the loop becomes:
y = None
while (x != y) and (i < t):
y = core(x)
i += 1
It doesn't much matter what you set y to in the main() function to start with, as long as it'll never be equal to x before the user has made a guess. 最初在main()函数中将y设置为什么都无所谓,只要在用户做出猜测之前永远不等于x。
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