| Symbol | Symbol Name | Meaning/Definition | Example |
|---|
| x | x variable | unknown value to find | when 2x = 4, then x = 2 |
≡ | equivalence | identical to | |
≜ | equal by definition | equal by definition | |
:= | equal by definition | equal by definition | |
~ | approximately equal | weak approximation | 11 ~ 10 |
≈ | approximately equal | approximation | sin(0.01) ≈ 0.01 |
∝ | proportional to | proportional to | f(x) ∝ g(x) |
∞ | lemniscate | infinity symbol | |
≪ | much less than | much less than | 1 ≪ 1000000 |
≫ | much greater than | much greater than | 1000000 ≫ 1
| ( ) | parentheses | calculate expression inside first | 2 * (3+5) = 16 |
[ ] | brackets | calculate expression inside first | [(1+2)*(1+5)] = 18 |
{ } | braces | set | |
⌊x⌋ | floor brackets | rounds number to lower integer | ⌊4.3⌋= 4 |
⌈x⌉ | ceiling brackets | rounds number to upper integer | ⌈4.3⌉= 5 |
x! | exclamation mark | factorial | 4! = 1*2*3*4 = 24 |
| x | | single vertical bar | absolute value | | -5 | = 5 |
f (x) | function of x | maps values of x to f(x) | f (x) = 3x+5 |
(f ∘g) | function composition | (f ∘g) (x) = f (g(x)) | f (x)=3x, g(x)=x-1 ⇒(f ∘g)(x)=3(x-1) |
(a,b)| open interval | (a,b) = {x | a < x < b} | x ∈ (2,6) |
[a,b] | closed interval | [a,b] = {x | a ≤ x ≤ b} | x ∈ [2,6] |
∆ | delta | change / difference | ∆t = t1 - t0 |
∆ | discriminant | Δ = b^2 - 4ac | |
∑ | sigma | summation - sum of all values in range of series | ∑ xi= x1+x2+...+xn |
∑∑ | sigma | double summation | |
∏ | capital pi | product - product of all values in range of series | ∏xi=x1∙x2∙...∙xn |
e | e constant / Euler's number | e = 2.718281828... | e = lim(1+1/x)x , x→∞< |
`γ | Euler-Mascheroni constant | γ = 0.527721566... | |
φ | golden ratio | golden ratio constant | |
π | pi constant | π = 3.141592654... is the ratio between the circumference and diameter of a circle | c = π·d = 2·π·r |
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