| 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 |
y ∝ x when y = kx, k constant |
| ∞ |
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 = b2 – 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 |