O(*): Landau symbol, indicating the asymptotic behavior of the function at the limit. It comes from the Greek letter ο.

Derivative function or differential

? : partial differential. From the Greek letter δ.

∫: Integral. It was invented by the German mathematician Leibniz at the end of 17, and originated from Latin alphabet? (long s)

? The relationship with S is equivalent to the relationship between the Greek letters σ and zeta. Although it is no longer used, it can still be seen on German hawksbill. This letter once existed in English, for example, "sinnish" was once written as "? Infurna? s”

? : Split operator. Hamilton, a British mathematician, first used it to express vector differential.

δ: Laplace operator. First used by the French mathematician Laplace, it is a simple symbol of Laplace equation. δ =? 2

Div: Divergence, which indicates the change (gushing or inflow) of a point in the vector field.

Rot: curl, which indicates the rotation of the field relative to a point in the vector field. From german Rotation.rot=? ×

Grad: gradient, indicating the rate of change of vector field in a certain direction. From german. grad =?