There are five special curves in postgraduate mathematics: Dirichlet function, symbolic function, integer function, hyperbolic sine function and hyperbolic tangent function.

1, Dirichlet function:

It is a periodic function, but there is no minimum positive period. Because all positive rational numbers are their periods.

2. Symbol function:

y = SGN x； x & lt0，y =- 1； When x=0, y = 0；; x & gt0，y= 1。

3. Integer function:

Y=[x], the graph of this function is stepped, sometimes called ladder curve.

4, hyperbolic sine function:

Y = sh x = (e x-e (-x))/2, and this function is a monotonically increasing odd function. The curve finally approaches y = 1/2 (e x), corresponding inverse function, inverse hyperbolic sine function, y = arsh x.

5, hyperbolic tangent function:

Its domain is negative infinity, positive infinity, y= th x = sh x/ch x, and it is bounded. As shown in the figure, the upper bound is 1 and the lower bound is-1.

Extended data:

Postgraduate mathematics, postgraduate subjects, according to the different requirements of engineering, economics, management disciplines and majors for graduate students' mathematical knowledge and ability.

There are three kinds of math test papers for postgraduate entrance examination, among which Math I and Math II are engineering, and Math III is management. There are specific regulations on the types of test papers used by different majors.

Baidu encyclopedia-postgraduate mathematics