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   jn.3p    ( 3 )

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Пролог (Prolog)

This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

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Имя (Name)

j0, j1, jn — Bessel functions of the first kind

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Синопсис (Synopsis)

#include <math.h>

       double j0(double x);
       double j1(double x);
       double jn(int n, double x);

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Описание (Description)

The j0(), j1(), and jn() functions shall compute Bessel functions
       of x of the first kind of orders 0, 1, and n, respectively.

       An application wishing to check for error situations should set
       errno to zero and call feclearexcept(FE_ALL_EXCEPT) before
       calling these functions. On return, if errno is non-zero or
       fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW |
       FE_UNDERFLOW) is non-zero, an error has occurred.

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Возвращаемое значение (Return value)

Upon successful completion, these functions shall return the
       relevant Bessel value of x of the first kind.

       If the x argument is too large in magnitude, or the correct
       result would cause underflow, 0 shall be returned and a range
       error may occur.

       If x is NaN, a NaN shall be returned.

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Ошибки (Error)

These functions may fail if:

       Range Error The value of x was too large in magnitude, or an
                   underflow occurred.

                   If the integer expression (math_errhandling &
                   MATH_ERRNO) is non-zero, then errno shall be set to
                   [ERANGE].  If the integer expression
                   (math_errhandling & MATH_ERREXCEPT) is non-zero, then
                   the underflow floating-point exception shall be
                   raised.

       No other errors shall occur.

       The following sections are informative.

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Примеры (Examples)

None.

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Использование в приложениях (Application usage)

On error, the expressions (math_errhandling & MATH_ERRNO) and
       (math_errhandling & MATH_ERREXCEPT) are independent of each
       other, but at least one of them must be non-zero.

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Обоснование (Rationale)

None.

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Будущие направления (Future directions)

None.

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Смотри также (See also)

feclearexcept(3p), fetestexcept(3p), isnan(3p), y0(3p)

       The Base Definitions volume of POSIX.1‐2017, Section 4.20,
       Treatment of Error Conditions for Mathematical Functions,
       math.h(0p)

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