Why there is no π(3.14....) number as constant or function?

[MaMrEzO]

Just out of curiosity, I'd looked into your library, and just found one usage of Pi number as follow: Pi usage in code func (d Decimal) satan() Decimal But using NewFromFloat may not get us actual Pi number as expected as 3.14159265358979323846264338327950288419716939937510582097494459, I'd test it and got 3.141592653589793, But we can do NewFormString("3.114159265358979323846264338327950288419716939937510582097494459") then we have 3.14159265358979323846264338327950288419716939937510582097494459 as result. The function must be:

// satan reduces its argument (known to be positive)
// to the range [0, 0.66] and calls xatan.
func (d Decimal) satan() Decimal {
	Morebits := NewFromFloat(6.123233995736765886130e-17) // pi/2 = PIO2 + Morebits
	Tan3pio8 := NewFromFloat(2.41421356237309504880)      // tan(3*pi/8)
	pi, _ := NewFromString("3.14159265358979323846264338327950288419716939937510582097494459")

	if d.LessThanOrEqual(NewFromFloat(0.66)) {
		return d.xatan()
	}
	if d.GreaterThan(Tan3pio8) {
		return pi.Div(NewFromFloat(2.0)).Sub(NewFromFloat(1.0).Div(d).xatan()).Add(Morebits)
	}
	return pi.Div(NewFromFloat(4.0)).Add((d.Sub(NewFromFloat(1.0)).Div(d.Add(NewFromFloat(1.0)))).xatan()).Add(NewFromFloat(0.5).Mul(Morebits))
}

And even a function to provide Pi number:

func PiNumber() Decimal{
  pi, _ := NewFromString("3.14159265358979323846264338327950288419716939937510582097494459")
  return pi
}

[mwoss]

Hi @MaMrEzO. You're right. There is no reason why there is no such function or constant. Good catch! I will add this to our backlog. Thank a lot :3