can detect it through the isNaN () method of the Global object (Gobal). Two Nan howeverValues are not mutually equal. The following example://---------------------------------------------------------Operation and detection of Nan//---------------------------------------------------------VarV1 = ten * ' A ';V2 = ten * ' A ';Document.writeln (isNaN (v1));Document.writeln (isNaN (v2));Document.writeln (v1 = = v2);
The Infinity of Global Objects (Gobal)
#define INF 0x3f3f3f3f
0x3f3f3f3f decimal is 1061109567, that is, 10^9 level (and 0x7fffffff (32-bit int maximum) an order of magnitude), and the general situation of the data are less than 10^9, So it can be used as infinity without the case that the data is larger than infinity.
On the other hand, since the general data is not greater than 10^9, when we add infinity
node.By default, a faulty resource can be run on a node only after the administrator manually resets the resource fault count (after the fault cause is fixed.However, you can set the failure-timeout option of the resource to invalidate the fault count. If you set migration-threshold = 2 and failure-timeout = 60 s, the resource will be migrated to the new node after two failures, and it may be allowed to move back after one minute (depending on stickiness and constraint scores ).There are two ex
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Article, where the information may have evolved or changed.
Go source reading notes (Math.1)
Abs.go
Func Abs (x float64) float64
PackageMath//Abs returns the absolute value of x.////Special cases is://Abs (±inf) = +inf//Abs (Nan) = NanfuncAbs (xfloat64)float64{//Todo:once golang.org/issue/13095 is fixed, change this to: //Return Float64frombits (Float64bits (x) ^ (1 generates better code and can also be inlined: ifX 0{return-X}ifx = =0{return0 //Return correctly
Numbers, cardinality and representations
integerIntegers are these familiar numbers ...,-1, 0, +1, +2, .... Integer values are also referred to as ' complete ' and are divided into positive numbers (1 to infinity), negative numbers (-1 to negative infinity), 0 (0), non-negative (0 or positive), and rare non-positive (0 or negative). The difference between positive and non-negative numbers is usually ve
1.js Digital-nan and Infinity1, in JS, there is a special value, called Nan (not a number), indicating that the operation to return a numeric value is not returned, such as 0 divided by 0 operation, in other languages will be reported errors or exceptions, and in JS, 0/0 will return Nan, do not interrupt code execution.0/0; //NaN2. Any operation involving Nan will return Nan, for example1 + 0/0; //NaN3. Nan is not equal to any value, including itself, for exampleconsole.log(NaN == NaN); //fals
) 0*1.012*20
The number 10.0 can be expressed as the ending number of 1.01, and the index is 3: (-1) 0*1.012*23
Special Number
Except for the standard range of values allowed by encoding (for float, from 1.4e-45 to 3.4028235e + 38 ), there are also some special values that represent infinity, negative infinity,-0, and Nan (which represent "not a number. The existence of these values is to use a numb
To create the syntax for the number object:var myNum = new number (value);var myNum = number (value);When number () and operator new are used as constructors, it returns a newly created number object. If you do not use the new operator to call number () as a function, it will convert its arguments to an original value, and return this value (NaN if the conversion fails).Max_valueThe Max_value property is the largest number that can be represented in JavaScript. It has an approximate value of 1.7
follows:
> Number ("foo")
NaN
Another way to detect Nan is to use Nan as the only value that is strictly not equal to itself:
Copy Code code as follows:
function Myisnan (value) {
return value!== value;
}
Another more understandable approach is to check that the value is a numeric type before using isNaN (). This avoids the problem of implicit conversions.
Copy Code code as follows:
function MyIsNaN2 (value) {
return typeof value
, and is the nether Open, upper bound closed. (Why is it so defined?) InnoDB officially defined)Here's an example from the manual to see what is Next-key lock. If the row of an index has 10,11,13,20Then the possible Next-key lock includes:(Infinity, 10](10,11](11,13](13,20](20, Infinity) (Why is infinity here not closed?) You don't get home in math ~ ~)All right,
exponent is used, and 52 digits represent the mantissa. The IEEE floating-point values are formatted as shown in Figure 1.
Figure 1. IEEE 754 format for floating-point numbers
Because there are many ways to represent a given number in a scientific notation, you normalize the floating-point numbers so that you can use a decimal number with a base of 2 and a decimal point to the left of the dot to indicate that you need to adjust the exponent to get the numbers you want. So, for example, the
noting that although some JavaScript interpreters support the octal representation of the beginning of 0, but the ECMAScript standard is not supported, So try not to use octal notation to avoid problems with porting.Floating-point Direct volumeFloating-point direct quantities are represented as: [digits][.digits][(E|e) [(+|-)]digits], such as ①3.14, ②6.02e23, ③.22e-23//0.22x10-23Arithmetic operations in JSJS not only supports the common addition (+) minus (-) multiplication (*) except (*) and r
the return value. If the result is Nan, then the ToString () method is invoked before the preceding rule is applied. The object variable becomes a numeric variable.
Small quiz:
Perform a post increment operation on the following types of values, and what is the result?
"2″, 02DD", "", false, 22.5, + "",-false, +new Date ()
3. Addition Operation operator
The plus operator operator is also used in JavaScript for string connectors, so the rules for the plus operator are divided into two situa
constraints: (constraints)
Location constraints: locations
Define the relationship between resources and nodes. For example, the node on which resources tend to run.
The defined range is positive infinity (INF) to negative infinity (-INF ).
Positive infinity indicates that the node runs as long as it may run on the current node. Negative
) index Sign
52 bits (0 - 51) 11 bits (50 - 62) 1 bit (63)
PrecisionAn integer (without the decimal point or exponential Notation) can contain up to 15 digits.The maximum number of decimal places is 17, but the floating point operation is not always 100% accurate:Instance
var x = 0.2+0.1; // result will be 0.30000000000000004
Octal and hexadecimalIf the prefix is 0, JavaScript interprets the numeric constant as the octal number. If the prefix is 0 and "x", it is interpreted as the hexadecimal nu
1. Basic typesThere are several basic data types for Javascript:
Number
String:
Boolean:
Undefined: When you access a non-existent variable, you get it undefined . It is also available when you define a variable but do not assign it a value undefined . JavaScript automatically initializes the variable to that value, and the undefined type has only one value undefined .
Null: means that the variable has no value or is empty.
Except for the above type, the o
e> 0, on the interval (a-r,a + R), satisfies
F (x)-a
It is said that a is the limit of f (x) on (a-r,a + R)
2) tend to the infinite function limit, defined: The function is greater than a certain "positive x" has a definition (function interval is (X, Infinity)), for all e > 0, when the |x| > x (function defined) satisfies
|f (x)-a |
3) The function limit is based on the function model, that is, a two-dimensional change process, the independent vari
One, variable1. Variable name: A combination of letters, numbers, underscores, and dollar signs that cannot begin with a number. is case sensitive. 2, declaring variables: var variable name = variable value;Second, operator1, arithmetic operators: +-*/(non-divisible)% (modulo) + +--+ = =III. Basic data types1. Basic data type: Number , string , boolean, undefined, null undefined: non-existent variablenull: No value or null value====================2. typeof returns a string of data type3, the v
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