Plus sign andminus sign(+and -) are the concepts used to represent positive and negative andadditionandsubtractionThe mathematical symbol for the operation of.Their use has expanded to many other meanings.Add and subtract are Latin for "more" and "less", respectively.
Chinese name
Positive sign
Foreign name
Plus sign
Pinyin
zhènɡ hào
Origin
The Book of the Later Han Dynasty - Preface to the Empress
The plus and minus signs (+and -) are mathematical symbols used to represent the concepts of positive and negative, as well as the operations of addition and subtraction.Their use has expanded to many other meanings.Add and subtract are Latin for "more" and "less", respectively.
history
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Although these two symbols seem to us as familiar as the alphabet or Arabic numerals, they are not so old.For example, the Egyptian hieroglyph symbol is similar to a leg walking along the direction of text writing (Egypt can write from right to left or from left to right), and the negative sign indicates subtraction:
Nicole Oresme's 14th century manuscripts may be one of the earliest uses of the plus sign "+".
In Europe at the beginning of the 15th century, the letters "P" and "M" were commonly used.The symbol (P with a line p ̄ represents the plus sign; M with a linem̄, representing the minus sign) first appeared in Luca Pacioli's mathematical outline (published in Venice in 1494)+Is a simplification of the Latin "et" (equivalent to the&sign)-Can be derived from the waveform character written on m for indicating subtraction;Or it may come from its own abbreviated version;Johannes Widmann mentioned the symbols - and+as minus signs and mer (modern German mehr; "more") in his 1489 paper. They are not used for addition and subtraction here, but for surplus and deficit;Their first use in the modern sense appeared in a book by Henricus Grammateus in 1518.
In 1557, Robert Recorde, the designer of the equal sign, introduced addition and subtraction to Britain in "The Grindstone of Victor": "The first one is often used as the other two symbols, and more often: the other one did it - and less often".
plus
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The plus sign (+) is an operator, representing addition, such as 2+3=5.This symbol can be used when it is necessary to emphasize the enthusiasm of numbers, especially when compared with negative numbers (+5 vs. - 5).
The plus sign can also indicate many other operations, depending on the mathematical system under consideration.Many algebraic structures have operations called or equivalent to addition.The general use of the plus sign only indicates the swap operation.In addition, the plus sign can also mean:
(1) XOR (usually written ⊕): 1+1=0, 1+0=1
(2) Logic separation (usually written as ∨): 1+1=1, 1+0=1
Used in primary education
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Some primary school teachers use raised signs in front of numbers to indicate positive or negative numbers.For example, subtracting - 5 from 3 may be read as "positive three decimate negative 5" and displayed as
It becomes 3+5=8.
Even
It becomes
。
Used as a qualifier
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In the grading system (such as exam marking), the plus sign indicates one level above, and the minus sign indicates one level below.For example, B - ("B minus") is one grade lower than B.Sometimes this extends to two plus or minus signs;For example, A++is two levels higher than A.
Sometimes abbreviated as+ve and - ve.
In mathematics, the unilateral limit x → a+means that x approaches a from the right, and x → a - means that x approaches a from the left.For example, when x is close to 0, x-1 →+∞ when x → 0+and x-1 → - ∞ when x → 0 -.
Blood type usually indicates the presence or absence of Rh factor by adding or subtracting;For example, A+represents type A blood with Rh factor, while B - represents type B blood without Rh factor.
In music, enhanced chords are represented by a plus sign, although this is not very common because there are other ways to spell these chords.For example, "C+" is read as "C Enhanced Chord".Also used as superscript.
For calculation
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(1) The plus and minus signs can be used for many other purposes in calculation except for the normal mathematical usage.
(2) The plus and minus signs are usually used in the tree view of the computer screen to show whether the folder is collapsed.
(3) In some programming languages, the concatenation of strings is written as "a"+"b", and "ab" is generated.
(4) In most programming languages, the ASCII hyphen - is used for subtraction and negation.In APL, the minus sign (Unicode U+00AF) is used to indicate a negative number, such as 3.In J, negative numbers are represented by underscores, as shown in _5.
(5) In C and othersComputer programming languageIn, two plus signs represent the increment operator, and two minus signs represent the decrement operator.For example, x++means "the value of x increases by 1", and x - means "the value of x decreases by 1".Through extension, sometimes "++" is used in computing terms to indicate improvement, just like C++language.
(6) In regular expressions, "+" is used to indicate "1 or more" in the pattern to match.For example, "x+" means "one or more letters x".
(7) There is no concept of negative zero in mathematics, but there may be a representation of zero in calculation.In the IEEE floating point standard, 1/- 0 is negative infinity (- ∞) and 1/0 is positive infinity (∞).[1]
Other uses
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(1) In chemistry, the minus sign is used in a single covalent bond between two atoms.
(2) The subscript plus and minus signs are used as diacritical marks in the international phonetic alphabet to indicate the advanced or indented expression of speech.
(3) The minus sign is also used for tones in the orthography of Dan, Krumen, Calabro, Wan Wan, Yuri, W è, Nyabwa and Godi é.The Unicode character used for tonal letters (U+02D7) is different from the mathematical minus sign.
(4) In the algebraic symbol used to record the chess game, the plus sign (+) is used to indicate the action of putting the opponent into the check.Sometimes double plus (++) is used to indicate double checking.The combination of plus and minus signs is used to evaluate movement (+/-,+/=,=/+, -/+).
