Symbol type
1, quantity symbol
For example, pi (π, 3. 14 159265358979), natural rate (e, 2.7 1828), Fibonacci golden section (φ, 0.6 18033), imaginary number (.
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. Relationship symbols
For example, "=" is an equal sign, "≈" is an approximate sign, "≦" is an unequal sign and ">" is a greater than sign. "
4. Natural symbols
Such as plus sign, minus sign, plus sign (and the corresponding minus sign? ) )
Step 5 omit symbols
Such as triangle (△), right triangle (Rt△), sine (see trigonometric function), hyperbolic sine function (sinh), function of x (f(x)), limit (lim) and angle (∞).