infinity

Why do dates at infinity look like NAs but act like dates? [duplicate]

由 故事扮演 提交于 2019-11-30 17:28:45
This question already has an answer here: R `Inf` when it has class `Date` is printing `NA` 1 answer I was trying to figure out the best way to deal with Postgresql's ability to represent Infinity and -Infinity in their timestamps when using RPostgreSQL to bring data over into R. Along the way I found some strange behavior when trying to represent infinite dates in R. I can attempt to create a date at negative and positive infinity in the following manner: ❥ as.Date(-1/0, origin="1970-01-01") [1] NA ❥ as.Date(1/0, origin="1970-01-01") [1] NA They both appear to be NAs. However when comparing

What are the INFINITY constants in Java, really?

由 六月ゝ 毕业季﹏ 提交于 2019-11-30 11:47:22
问题 I just recently ran across the constants in the primitive type wrapper classes like Double.POSITIVE_INFINITY and Double.NEGATIVE_INFINITY . In the API, it defines the first as: A constant holding the positive infinity of type double. It is equal to the value returned by Double.longBitsToDouble(0x7ff0000000000000L). The others have definitions along these same lines. What I'm having trouble with is understanding what these constants actually are. They can't actually be or represent positive

What do these three special floating-point values mean: positive infinity, negative infinity, NaN?

由 我的未来我决定 提交于 2019-11-30 09:00:36
How can we use them in our codes, and what will cause NaN(not a number)? Cameron This may be a good reference if you want to learn more about floating point numbers in Java. Positive Infinity is a positive number so large that it can't be represented normally. Negative Infinity is a negative number so large that it cannot be represented normally. NaN means "Not a Number" and results from a mathematical operation that doesn't yield a number- like dividing 0 by 0. In Java, the Double and Float classes both have constants to represent all three cases. They are POSITIVE_INFINITY, NEGATIVE_INFINITY

Python Infinity - Any caveats?

由 对着背影说爱祢 提交于 2019-11-30 05:51:23
问题 So Python has positive and negative infinity: float("inf"), float("-inf") This just seems like the type of feature that has to have some caveat. Is there anything I should be aware of? 回答1: You can still get not-a-number (NaN) values from simple arithmetic involving inf : >>> 0 * float("inf") nan Note that you will normally not get an inf value through usual arithmetic calculations: >>> 2.0**2 4.0 >>> _**2 16.0 >>> _**2 256.0 >>> _**2 65536.0 >>> _**2 4294967296.0 >>> _**2 1.8446744073709552e

Why do dates at infinity look like NAs but act like dates? [duplicate]

由 邮差的信 提交于 2019-11-30 01:51:31
问题 This question already has an answer here : R `Inf` when it has class `Date` is printing `NA` (1 answer) Closed last year . I was trying to figure out the best way to deal with Postgresql's ability to represent Infinity and -Infinity in their timestamps when using RPostgreSQL to bring data over into R. Along the way I found some strange behavior when trying to represent infinite dates in R. I can attempt to create a date at negative and positive infinity in the following manner: ❥ as.Date(-1/0

What are the INFINITY constants in Java, really?

由 萝らか妹 提交于 2019-11-30 01:23:37
I just recently ran across the constants in the primitive type wrapper classes like Double.POSITIVE_INFINITY and Double.NEGATIVE_INFINITY . In the API, it defines the first as: A constant holding the positive infinity of type double. It is equal to the value returned by Double.longBitsToDouble(0x7ff0000000000000L). The others have definitions along these same lines. What I'm having trouble with is understanding what these constants actually are. They can't actually be or represent positive/negative infinities, because the system is by nature finite. Is it just some arbitrary setting of bits

Represent infinity as an integer in Python 2.7

由 瘦欲@ 提交于 2019-11-29 19:06:31
问题 I am wondering how to define inf and -inf as an int in Python 2.7. I tried and it seems inf and -inf only work as a float . a = float('-inf') # works b = float('inf') # works c = int('-inf') # compile error, ValueError: invalid literal for int() with base 10: 'inf' d = int('inf') # compile error, ValueError: invalid literal for int() with base 10: 'inf' 回答1: To summarise what was said in the comments There is no way to represent infinity as an integer in Python. This matches the behaviour of

What do these three special floating-point values mean: positive infinity, negative infinity, NaN?

由 无人久伴 提交于 2019-11-29 12:52:35
问题 How can we use them in our codes, and what will cause NaN(not a number)? 回答1: This may be a good reference if you want to learn more about floating point numbers in Java. Positive Infinity is a positive number so large that it can't be represented normally. Negative Infinity is a negative number so large that it cannot be represented normally. NaN means "Not a Number" and results from a mathematical operation that doesn't yield a number- like dividing 0 by 0. In Java, the Double and Float

Modeling infinity for the largest double value

由 为君一笑 提交于 2019-11-29 11:39:13
问题 The question is about modeling infinity in C++ for the double data type. I need it in a header file, so we cannot use functions like numeric_limits . Is there a defined constant that represents the largest value? 回答1: floating point numbers(such as doubles) can actually hold positive and negative infinity. The constant INFINITY should be in your math.h header. Went standard diving and found the text: 4 The macro INFINITY expands to a constant expression of type float representing positive or

How are Inf and NaN implemented?

由 跟風遠走 提交于 2019-11-29 06:32:47
As mathematical concepts, I am well aware of what inf and nan actually are. But what I am really interested in is how they are implemented in programming languages. In python, I can use inf and nan in arithmetic and conditional expressions, like this: >>> nan = float('nan') >>> inf = float('inf') >>> 1 + inf inf >>> inf + inf inf >>> inf - inf nan This would lead me to believe that python internally has a special reserved bit sequence for these two mathematical quantities, and no other number can assume these positions. Is my assumption correct? Can you please enlighten me in this regard? If
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