// series near these points.
//
// ctan(z) = -i ctanh(iz).
//
// ACCURACY:
//
//                      Relative error:
// arithmetic   domain     # trials      peak         rms
//    DEC       -10,+10      5200       7.1e-17     1.6e-17
//    IEEE      -10,+10     30000       7.2e-16     1.2e-16
// Also tested by ctan * ccot = 1 and catan(ctan(z))  =  z.

// Tan returns the tangent of x.

//
// Where k is an arbitrary integer.
//
// catan(z) = -i catanh(iz).
//
// ACCURACY:
//
//                      Relative error:
// arithmetic   domain     # trials      peak         rms
//    DEC       -10,+10      5900       1.3e-16     7.8e-18
//    IEEE      -10,+10     30000       2.3e-15     8.5e-17
// The check catan( ctan(z) )  =  z, with |x| and |y| < PI/2,

func NewChan(dir ChanDir, elem Type) *Chan {
	return &Chan{dir: dir, elem: elem}
}

// Dir returns the direction of channel c.
func (c *Chan) Dir() ChanDir { return c.dir }

// Elem returns the element type of channel c.
func (c *Chan) Elem() Type { return c.elem }

func (c *Chan) Underlying() Type { return c }

		Tan3pio8 = 2.41421356237309504880      // tan(3*pi/8)
	)
	if x <= 0.66 {
		return xatan(x)
	}
	if x > Tan3pio8 {
		return Pi/2 - xatan(1/x) + Morebits
	}
	return Pi/4 + xatan((x-1)/(x+1)) + 0.5*Morebits
}

// Atan returns the arctangent, in radians, of x.
//
// Special cases are:
//
//	Atan(±0) = ±0
//	Atan(±Inf) = ±Pi/2
func Atan(x float64) float64 {
	if haveArchAtan {
		return archAtan(x)

	totr, tots int
	totLock    sync.Mutex
	nc         *Chan
)

func init() {
	nc = new(Chan)
}

func changeNproc(adjust int) int {
	nprocLock.Lock()
	nproc += adjust
	ret := nproc
	nprocLock.Unlock()
	return ret
}

func mkchan(c, n int) []*Chan {
	ca := make([]*Chan, n)
	for i := 0; i < n; i++ {
		cval = cval + 100
		ch := new(Chan)
		ch.sc = make(chan int, c)
		ch.rc = ch.sc
		ch.sv = cval

func NewChan(dir ChanDir, elem Type) *Chan {
	return &Chan{dir: dir, elem: elem}
}

// Dir returns the direction of channel c.
func (c *Chan) Dir() ChanDir { return c.dir }

// Elem returns the element type of channel c.
func (c *Chan) Elem() Type { return c.elem }

func (c *Chan) Underlying() Type { return c }

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

type xyz struct {
    ch chan
} // ERROR "unexpected .*}.* in channel type|missing channel element type"

func Foo(y chan) { // ERROR "unexpected .*\).* in channel type|missing channel element type"
}

func Bar(x chan, y int) { // ERROR "unexpected comma in channel type|missing channel element type"

	-5.38695755929454629881e7, // 0xc189afe03cbe5a31
}

// Tan returns the tangent of the radian argument x.
//
// Special cases are:
//
//	Tan(±0) = ±0
//	Tan(±Inf) = NaN
//	Tan(NaN) = NaN
func Tan(x float64) float64 {
	if haveArchTan {
		return archTan(x)
	}
	return tan(x)
}

func tan(x float64) float64 {
	const (

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

type Chan[T any] chan Chan[T]

func (ch Chan[T]) recv() Chan[T] {
	return <-ch
}

func main() {
	ch := Chan[int](make(chan Chan[int]))
	go func() {
		ch <- make(Chan[int])
	}()
	ch.recv()

// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package p

type C0 interface{ int }
type C1 interface{ chan int }
type C2 interface{ chan int | <-chan int }
type C3 interface{ chan int | chan float32 }
type C4 interface{ chan int | chan<- int }
type C5[T any] interface{ ~chan T | chan<- T }

func _[T any](ch T) {