mathematical symbol

The invention and use of mathematical symbols are later than numbers, but there are many more numbers. Now there are more than 200 commonly used ones, and there are more than 20 in junior high school math books. They all had an interesting experience.

For example, there used to be several kinds of plus signs, but now the+sign is widely used.

The number "+"is derived from the Latin "et" (meaning "harmony"). /kloc-in the 6th century, Italian scientist Nicolo Tartaglia used the first letter of "piu" (meaning "addition") to indicate addition, and the grass was "μ", which finally became the number "+".

The number "-"evolved from the Latin word "minus", abbreviated as m, and then omitted the letter, it became "-".

It is also said that wine merchants use "-"to indicate how much wine is sold in barrels. Later, the new wine was poured into the barrel, and a vertical line was added after the "-",indicating that the original line was erased and it became a+sign.

In the 15th century, German mathematician Wei Demei officially determined+as a plus sign and-as a minus sign.

Multiplication has been used for more than a dozen times, and now there are two commonly used. One is "x", which was first proposed by British mathematician orcutt on 163 1; One is the British mathematician heriott. Leibniz, a German mathematician, thinks that the symbol "×" is very similar to the Latin letter "X", so he opposes the use of this symbol. He himself proposed to use "п" to represent multiplication. But this symbol is now applied to set theory.

/kloc-In the 8th century, American mathematician Audley decided to use "×" as the multiplication symbol. He thinks that "×" is an oblique writing of "+",which is another symbol for increase.

⊙ Originally used as a minus sign, it has been popular in continental Europe for a long time. It was not until 163 1 that the British mathematician Orqut used ":"to indicate division or comparison, while others used "-"(except lines) to indicate division. Later, the Swiss mathematician Laha formally defined "∫" in his Algebra.

The square root number was once represented by the combination of the first and last letters of the Latin "radical". /kloc-At the beginning of the 0/7th century, the French mathematician Descartes used "√" for the first time in his Geometry. "R" is derived from the Latin word line "R", and "-"is a closed line.

/kloc-in the 6th century, the French mathematician Viette used "=" to indicate the difference between two quantities. However, Le Calder, a professor of mathematics and rhetoric at Oxford University in England, thinks that it is most appropriate to use two parallel and equal straight lines to indicate that two numbers are equal, so he started to use the symbol "=" from 1540.

159 1 year, the French mathematician Veda used this symbol extensively in diamonds, and it was gradually accepted by people. /kloc-The symbol "=" was widely used in Leibniz, Germany in the 0/7th century. He also used "∽" to indicate similarity and ""to indicate congruence in geometry.

Greater than sign ">" and less than sign "

Mathematical symbols generally have the following kinds:

The sign of (1) quantity: I, 2+I, A, X, natural logarithm base E, pi ∏.

(2) Operation symbols: such as plus sign (+), minus sign (-), multiplication sign (× or), division sign (÷ or/), union of two sets (∩), intersection (∩), root sign (√), logarithm (log, lg, ln.

(3) relational symbols: such as "=" is an equal sign, "≈" is an approximate sign, "≦" is an unequal sign and ">" is a greater than sign. "

(4) Combination symbols: such as parentheses "()" square brackets "[]", and curly braces "{}" enclose the line "-".

(5) Natural symbols: such as positive sign "+",negative sign "-"and absolute value symbol "∨"

(6) Omitting symbols: triangle (△), sine (sin), function of x (f(x)), limit (lim), because (∵), so (∴), sum (∏) and multiplication (∏), all from N elements at once. ) and so on.

symbolic meaning

∞ infinity

circumference ratio

│x│ The absolute value of the function

Set up and merge

Set intersection

≥ greater than or equal to

≤ less than or equal to

≡ Constant is equal to or congruent with.

Ln(x) logarithm based on e

Lg(x) logarithm based on 10

Integer function on floor (x)

Integer function under ceil(x)

X mod y of remainder

Decimal part x-floor(x)

∫f(x)δx indefinite integral

∫ [a: b] The definite integral of f (x) Δ x a to b

If p is true, it is equal to 1, otherwise it is equal to 0.

∑[ 1≤k≤n]f(k) and n can be extended to many situations.

For example, ∑ [n is a prime number] [n

∑∑[ 1≤i≤j≤n]n^2

lim f(x)(x-& gt； ? ) seek the limit

M-order derivative function of f(z) f about z

C(n:m) combination number, where m is taken from n.

P(n:m) permutation number

Divisible by n

M⊥n coprime

A ∈ A a belongs to set A.