Documentation

Mathlib.Data.Complex.Trigonometric

Trigonometric and hyperbolic trigonometric functions #

This file contains the definitions of the sine, cosine, tangent, hyperbolic sine, hyperbolic cosine, and hyperbolic tangent functions.

def Complex.sin (z : ) :

The complex sine function, defined via exp

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    def Complex.cos (z : ) :

    The complex cosine function, defined via exp

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      def Complex.tan (z : ) :

      The complex tangent function, defined as sin z / cos z

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        def Complex.cot (z : ) :

        The complex cotangent function, defined as cos z / sin z

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          def Complex.sinh (z : ) :

          The complex hyperbolic sine function, defined via exp

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            def Complex.cosh (z : ) :

            The complex hyperbolic cosine function, defined via exp

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              def Complex.tanh (z : ) :

              The complex hyperbolic tangent function, defined as sinh z / cosh z

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                def Real.sin (x : ) :

                The real sine function, defined as the real part of the complex sine

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                  def Real.cos (x : ) :

                  The real cosine function, defined as the real part of the complex cosine

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                    def Real.tan (x : ) :

                    The real tangent function, defined as the real part of the complex tangent

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                      def Real.cot (x : ) :

                      The real cotangent function, defined as the real part of the complex cotangent

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                      • x.cot = (↑x).cot.re
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                        def Real.sinh (x : ) :

                        The real hypebolic sine function, defined as the real part of the complex hyperbolic sine

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                          def Real.cosh (x : ) :

                          The real hypebolic cosine function, defined as the real part of the complex hyperbolic cosine

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                            def Real.tanh (x : ) :

                            The real hypebolic tangent function, defined as the real part of the complex hyperbolic tangent

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                              @[simp]
                              @[simp]
                              theorem Complex.ofReal_sinh (x : ) :
                              @[simp]
                              theorem Complex.sinh_ofReal_im (x : ) :
                              (Complex.sinh x).im = 0
                              @[simp]
                              theorem Complex.ofReal_cosh (x : ) :
                              @[simp]
                              theorem Complex.cosh_ofReal_im (x : ) :
                              (Complex.cosh x).im = 0
                              @[simp]
                              @[simp]
                              @[simp]
                              theorem Complex.ofReal_tanh (x : ) :
                              @[simp]
                              theorem Complex.tanh_ofReal_im (x : ) :
                              (Complex.tanh x).im = 0
                              @[simp]
                              @[simp]
                              @[simp]
                              @[simp]
                              theorem Complex.sin_sub_sin (x y : ) :
                              Complex.sin x - Complex.sin y = 2 * Complex.sin ((x - y) / 2) * Complex.cos ((x + y) / 2)
                              theorem Complex.cos_sub_cos (x y : ) :
                              Complex.cos x - Complex.cos y = -2 * Complex.sin ((x + y) / 2) * Complex.sin ((x - y) / 2)
                              theorem Complex.sin_add_sin (x y : ) :
                              Complex.sin x + Complex.sin y = 2 * Complex.sin ((x + y) / 2) * Complex.cos ((x - y) / 2)
                              theorem Complex.cos_add_cos (x y : ) :
                              Complex.cos x + Complex.cos y = 2 * Complex.cos ((x + y) / 2) * Complex.cos ((x - y) / 2)
                              @[simp]
                              theorem Complex.ofReal_sin_ofReal_re (x : ) :
                              (Complex.sin x).re = Complex.sin x
                              @[simp]
                              theorem Complex.ofReal_sin (x : ) :
                              (Real.sin x) = Complex.sin x
                              @[simp]
                              theorem Complex.sin_ofReal_im (x : ) :
                              (Complex.sin x).im = 0
                              @[simp]
                              theorem Complex.ofReal_cos_ofReal_re (x : ) :
                              (Complex.cos x).re = Complex.cos x
                              @[simp]
                              theorem Complex.ofReal_cos (x : ) :
                              (Real.cos x) = Complex.cos x
                              @[simp]
                              theorem Complex.cos_ofReal_im (x : ) :
                              (Complex.cos x).im = 0
                              @[simp]
                              @[simp]
                              theorem Complex.cot_conj (x : ) :
                              ((starRingEnd ) x).cot = (starRingEnd ) x.cot
                              @[simp]
                              theorem Complex.ofReal_tan_ofReal_re (x : ) :
                              (Complex.tan x).re = Complex.tan x
                              @[simp]
                              theorem Complex.ofReal_cot_ofReal_re (x : ) :
                              (↑x).cot.re = (↑x).cot
                              @[simp]
                              theorem Complex.ofReal_tan (x : ) :
                              (Real.tan x) = Complex.tan x
                              @[simp]
                              theorem Complex.ofReal_cot (x : ) :
                              x.cot = (↑x).cot
                              @[simp]
                              theorem Complex.tan_ofReal_im (x : ) :
                              (Complex.tan x).im = 0
                              @[simp]
                              @[simp]
                              theorem Complex.cos_two_mul (x : ) :
                              Complex.cos (2 * x) = 2 * Complex.cos x ^ 2 - 1
                              theorem Complex.cos_sq (x : ) :
                              Complex.cos x ^ 2 = 1 / 2 + Complex.cos (2 * x) / 2
                              theorem Complex.exp_re (x : ) :
                              (Complex.exp x).re = Real.exp x.re * Real.cos x.im
                              theorem Complex.exp_im (x : ) :
                              (Complex.exp x).im = Real.exp x.re * Real.sin x.im

                              De Moivre's formula

                              @[simp]
                              theorem Real.sin_zero :
                              @[simp]
                              theorem Real.sin_neg (x : ) :
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                              theorem Real.cos_zero :
                              @[simp]
                              theorem Real.cos_neg (x : ) :
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                              theorem Real.cos_abs (x : ) :
                              theorem Real.sin_sub_sin (x y : ) :
                              Real.sin x - Real.sin y = 2 * Real.sin ((x - y) / 2) * Real.cos ((x + y) / 2)
                              theorem Real.cos_sub_cos (x y : ) :
                              Real.cos x - Real.cos y = -2 * Real.sin ((x + y) / 2) * Real.sin ((x - y) / 2)
                              theorem Real.cos_add_cos (x y : ) :
                              Real.cos x + Real.cos y = 2 * Real.cos ((x + y) / 2) * Real.cos ((x - y) / 2)
                              @[simp]
                              theorem Real.tan_zero :
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                              theorem Real.tan_neg (x : ) :
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                              theorem Real.sin_sq_add_cos_sq (x : ) :
                              Real.sin x ^ 2 + Real.cos x ^ 2 = 1
                              @[simp]
                              theorem Real.cos_sq_add_sin_sq (x : ) :
                              Real.cos x ^ 2 + Real.sin x ^ 2 = 1
                              theorem Real.cos_two_mul (x : ) :
                              Real.cos (2 * x) = 2 * Real.cos x ^ 2 - 1
                              theorem Real.cos_two_mul' (x : ) :
                              Real.cos (2 * x) = Real.cos x ^ 2 - Real.sin x ^ 2
                              theorem Real.cos_sq (x : ) :
                              Real.cos x ^ 2 = 1 / 2 + Real.cos (2 * x) / 2
                              theorem Real.cos_sq' (x : ) :
                              Real.cos x ^ 2 = 1 - Real.sin x ^ 2
                              theorem Real.sin_sq (x : ) :
                              Real.sin x ^ 2 = 1 - Real.cos x ^ 2
                              theorem Real.sin_sq_eq_half_sub (x : ) :
                              Real.sin x ^ 2 = 1 / 2 - Real.cos (2 * x) / 2
                              theorem Real.inv_one_add_tan_sq {x : } (hx : Real.cos x 0) :
                              (1 + Real.tan x ^ 2)⁻¹ = Real.cos x ^ 2
                              theorem Real.tan_sq_div_one_add_tan_sq {x : } (hx : Real.cos x 0) :
                              Real.tan x ^ 2 / (1 + Real.tan x ^ 2) = Real.sin x ^ 2
                              theorem Real.cos_three_mul (x : ) :
                              Real.cos (3 * x) = 4 * Real.cos x ^ 3 - 3 * Real.cos x
                              theorem Real.sin_three_mul (x : ) :
                              Real.sin (3 * x) = 3 * Real.sin x - 4 * Real.sin x ^ 3
                              theorem Real.sinh_eq (x : ) :

                              The definition of sinh in terms of exp.

                              @[simp]
                              @[simp]
                              theorem Real.sinh_neg (x : ) :
                              theorem Real.cosh_eq (x : ) :

                              The definition of cosh in terms of exp.

                              @[simp]
                              @[simp]
                              theorem Real.cosh_neg (x : ) :
                              @[simp]
                              theorem Real.cosh_abs (x : ) :
                              @[simp]
                              @[simp]
                              theorem Real.tanh_neg (x : ) :
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                              theorem Real.cosh_sq (x : ) :
                              Real.cosh x ^ 2 = Real.sinh x ^ 2 + 1
                              theorem Real.cosh_sq' (x : ) :
                              Real.cosh x ^ 2 = 1 + Real.sinh x ^ 2
                              theorem Real.sinh_sq (x : ) :
                              Real.sinh x ^ 2 = Real.cosh x ^ 2 - 1
                              theorem Real.cosh_three_mul (x : ) :
                              Real.cosh (3 * x) = 4 * Real.cosh x ^ 3 - 3 * Real.cosh x
                              theorem Real.sinh_three_mul (x : ) :
                              Real.sinh (3 * x) = 4 * Real.sinh x ^ 3 + 3 * Real.sinh x
                              theorem Real.cosh_pos (x : ) :

                              Real.cosh is always positive

                              theorem Real.cos_bound {x : } (hx : |x| 1) :
                              |Real.cos x - (1 - x ^ 2 / 2)| |x| ^ 4 * (5 / 96)
                              theorem Real.sin_bound {x : } (hx : |x| 1) :
                              |Real.sin x - (x - x ^ 3 / 6)| |x| ^ 4 * (5 / 96)
                              theorem Real.cos_pos_of_le_one {x : } (hx : |x| 1) :
                              theorem Real.sin_pos_of_pos_of_le_one {x : } (hx0 : 0 < x) (hx : x 1) :
                              theorem Real.sin_pos_of_pos_of_le_two {x : } (hx0 : 0 < x) (hx : x 2) :

                              Extension for the positivity tactic: Real.cosh is always positive.

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