這些你都知道嗎？以后給老外作報告的時候可千萬別再“The equation is like this…”, “The value is like this…”
有些公式不好寫，能看出來什么意思就行了。
1.Logic
∃there exist
∀for all
p⇒q p implies q / if p, then q
p⇔q p if and only if q /p is equivalent to q / p and q are equivalent
2.Sets
x∈A x belongs to A / x is an element (or a member) of A
x∉A x does not belong to A / x is not an element (or a member) of A
A⊂B A is contained in B / A is a subset of B
A⊃B A contains B / B is a subset of A
A∩B A cap B / A meet B / A intersection B
A∪B A cup B / A join B / A union B
A\B A minus B / the diference between A and B
A×B A cross B / the cartesian product of A and B
3. Real numbers
x+1 x plus one
x-1 x minus one
x±1 x plus or minus one
xy xy / x multiplied by y
(x-y)(x+y) x minus y, x plus y
= the equals sign
x=5 x equals 5 / x is equal to 5
x≠5 x (is) not equal to 5
x≡y x is equivalent to (or identical with) y
x>y x is greater than y
x≥y x is greater than or equal to y
x<y x is less than y
x≤y x is less than or equal to y
0<x<1 zero is less than x is less than 1
0≤x≤1 zero is less than or equal to x is less than or equal to 1
|x| mod x / modulus x
x2 x squared / x (raised) to the power 2
x3 x cubed
x4 x to the fourth / x to the power 4
xn x to the nth / x to the power n
x (−n) x to the (power) minus n
x的平方根(square) root x / the square root of x
x的三次根cube root (of) x
x的四次根fourth root (of) x
x的n次根nth root (of) x
(x+y)2 x plus y all squared
n! n factorial
x^x hat
x¯ x bar
x˜ x tilde
xi xi / x subscript i / x suffix i / x sub i
∑(i=1~n) ai the sum from i equals one to n ai / the sum as i runs from 1 to n of the ai
4. Linear algebra
‖x‖the norm (or modulus) of x
OA→OA / vector OA
OA¯ OA / the length of the segment OA
AT A transpose / the transpose of A
A−1 A inverse / the inverse of A
5. Functions
f(x) fx / f of x / the function f of x
f:S→T a function f from S to T
x→y x maps to y / x is sent (or mapped) to y
f’(x) f prime x / f dash x / the (first) derivative of f with respect to x
f”(x) f double-prime x / f double-dash x / the second derivative of f with respect to x
f”’(x) triple-prime x / f triple-dash x / the third derivative of f with respect to x
f (4) (x) f four x / the fourth derivative of f with respect to x
∂f/∂x1 the partial (derivative) of f with respect to x1
∂2f/∂x12 the second partial (derivative) of f with respect to x1
∫0∞ the integral from zero to infinity
limx→0the limit as x approaches zero
limx→0+the limit as x approaches zero from above
limx→0−the limit as x approaches zero from below
logey log y to the base e / log to the base e of y / natural log (of) y
lny log y to the base e / log to the base e of y / natural log (of) y