A few days ago, there was such an error in the definition of y1. I continued to write regardless of the change to y11. Today I forgot about this and rushed online to find out why. This y1 was defined in math.h. Continue to open math.h-corecrt_math.h
It is found that not only y1, but also j0, j1, jn, y0, yn are defined
effect:
Function: double j0 (double x)
j0 returns the Bessel function of the first kind of order 0 of x. It may signal underflow if x is too large.
Function: double j1 (double x)
j1 returns the Bessel function of the first kind of order 1 of x. It may signal underflow if x is too large.
Function: double jn (int n, double x)
jn returns the Bessel function of the first kind of order n of x. It may signal underflow if x is too large.
Function: double y0 (double x)
y0 returns the Bessel function of the second kind of order 0 of x. It may signal underflow if x is too large. If x is negative, y0 signals a domain error; if it is zero, y0 signals overflow and returns -∞.
Function: double y1 (double x)y1 returns the Bessel function of the second kind of order 1 of x. It may signal underflow if x is too large. If x is negative, y1 signals a domain error; if it is zero, y1 signals overflow and returns -∞.
Function: double yn (int n, double x)yn returns the Bessel function of the second kind of order n of x. It may signal underflow if x is too large. If x is negative, yn signals a domain error; if it is zero, yn signals overflow and returns -∞.
Probably means to return a Bezier function or something
reference:
Standard library header < math >
These are some more exotic mathematical functions .
参考链接：https://blog.csdn.net/lsyiii1112/article/details/102966950
I feel this is a legacy of history. . . . Write y11 manually next time