divide-by-zero

问题 I am using numpy.where , and I was wondering if there was a simply way to avoid calling the unused parameter. Example: import numpy as np z = np.array([-2, -1, 0, 1, -2]) np.where(z!=0, 1/z, 1) returns: array([-0.5, -1. , 1. , 1. , -0.5]) but I get a divide by zero warning because when z was 0, the code still evaluates 1/z even though it doesn't use it. 回答1: You can also turn off the warning and turn it back on after you are done using the context manager errstate: with np.errstate(divide=

问题 I have two lists a and b of equal length. I want to calculate the sum of their ratio: c = np.sum(a/b) how can I have a zero (0) value in the summation coefficient when there is division by zero? EDIT: Here a couple of answers I tested for my case, and still raise the error. Probably I am missing something. The aray that contains zero elements is counts : try: cnterr = (counts/np.mean(counts))*(((cnterr/counts)**2 + (meanerr/np.mean(counts))**2 ))**1/2 except ZeroDivisionError: cnterr =

问题 Now I'm not asking about the mathematical answer of dividing by zero, I want to what my computer does when it tries to divide by zero? I can see different answers depending on what level we look at? Looking at a high-level I expect the language specification may just say "hey you can't do that throw an error" Looking at an assembly level, will the CPU try to call the divide instruction when we try to divide by 0? If it does that'll take us to the machine code level. What happens now? Now if

问题 i need to execute this query in postgres but i couldn't get rid of this error ERROR: division by zero SQL state: 22012 here is the query : select id,rates_sum,rates_count from tbl_node order by rates_sum/rates_count DESC; i know i can add a small value to the rates_count but i get inaccurate values . Is there a way to make the postgres ignore this error ,or using if statement to check zeros and replace them with any number. and again the error in the order by clause. Thanks 回答1: Use a CASE

问题 If I type: int main() { return 0 % 0; } I get back an error: error C2124: divide or mod by zero What is the reason behind this? Isn't the answer zero? 回答1: In mathematics, x mod 0 is undefined, hence the error. 回答2: From C++ standard, section 5.5: If during the evaluation of an expression the result is not mathematically defined or not in the range of representable mathematical values for its type, the behavior is undefined. [...] Treatment of division by zero, forming a remainder using a

问题 I have a Class in python, with the following attributes: self.number1 = 0 self.number2 = 0 self.divided = self.number1/self.number2 This of course throws up the zero error: ZeroDivisionError: integer division or modulo by zero The idea is that I will increment number1 and number2 later on, but will self.divided be automatically updated? If it is auto updated then how do I get around the zero error? Thanks. 回答1: No, self.divided is a simple attribute and will not automatically update. For

问题 I have a program which deliberately performs a divide by zero (and stores the result in a volatile variable) in order to halt in certain circumstances. However, I'd like to be able to disable this halting, without changing the macro that performs the division by zero. Is there any way to ignore it? I've tried using #include <signal.h> ... int main(void) { signal(SIGFPE, SIG_IGN); ... } but it still dies with the message "Floating point exception (core dumped)". I don't actually use the value,

问题 C# novice here, when the int 'max' below is 0 I get a divide by zero error, I can see why this happens but how should I handle this when max is 0? position is also an int. private void SetProgressBar(string text, int position, int max) { try { int percent = (100 * position) / max; //when max is 0 bug hits string txt = text + String.Format(". {0}%", percent); SetStatus(txt); } catch { } } 回答1: int percent = 0 if (max != 0) percent = (100*position) / max 回答2: Well, that entirely depends on the

问题 I noticed that in Coq's definition of rationals the inverse of zero is defined to zero. (Usually, division by zero is not well-defined/legal/allowed.) Require Import QArith. Lemma inv_zero_is_zero: (/ 0) == 0. Proof. unfold Qeq. reflexivity. Qed. Why is it so? Could it cause problems in calculations with rationals, or is it safe? 回答1: The short answer is: yes, it is absolutely safe. When we say that division by zero is not well-defined, what we actually mean is that zero doesn't have a

问题 I am confused with how Scala handles division by zero. Here is a REPL code snippet. scala> 1/0 java.lang.ArithmeticException: / by zero ... 33 elided scala> 1.toDouble/0.toDouble res1: Double = Infinity scala> 0.0/0.0 res2: Double = NaN scala> 0/0 java.lang.ArithmeticException: / by zero ... 33 elided scala> 1.toInt/0.toInt java.lang.ArithmeticException: / by zero ... 33 elided As you can see in the above example, depending on how you divide by zero, you get one of the following: "java.lang