Quelle interval_trig.pvs Sprache: PVS

%% interval_trig.pvs

interval_trig : THEORY
BEGIN
  IMPORTING trig_fnd@trig_basic,
            trig_fnd@trig_approx,
            trig_fnd@trig_ineq,
            trig_fnd@tan_approx,
            trig_fnd@atan_approx,
            trig_fnd@trig_values,
            interval

  X,Y : VAR Interval
  x   : VAR real
  n   : VAR nat

  cos_error_pi_lbn_bound: LEMMA
    abs(cos_term(pi_lbn(n))(2*n+2)) <
    3.2^(4+4*n)/factorial(4+4*n)

  % Pi
  Pi(n) : (Pos?) = [|pi_lbn(n),pi_ubn(n)|]

  % Sin
  sin_npi2_pi2(n)(X) : Interval =
    [|sin_lb(lb(X),n),sin_ub(ub(X),n)|]

  sin_pi2_pi(n)(X) : Interval =
    [|sin_lb(ub(X),n),sin_ub(lb(X),n)|]

  sin_0_pi(n)(X) : Interval =
    [|min(sin_lb(lb(X),n),sin_lb(ub(X),n)),1|]

  % Cos
  cos_0_pi(n)(X) : Interval =
    [|cos_lb(ub(X),n),cos_ub(lb(X),n)|]

  cos_npi2_pi2(n)(X) : Interval =
    [|min(cos_lb(lb(X),n),cos_lb(ub(X),n)),1|]

  Cos(n)(X) : Interval =
      if    X << [|0,pi_lb_est(n)|]             then cos_0_pi(n)(X)
      elsif X << [|-pi_lb_est(n),0|]            then cos_0_pi(n)(Neg(X))
      elsif X << [|-pi_lb_est(n)/2,pi_lb_est(n)/2|] then cos_npi2_pi2(n)(X)
      else  [|-1-(3.2^(4+4*n)/factorial(4+4*n)),1|]
      endif

  Cos_fundamental: LEMMA
    Proper?(X) AND
    X << Y IMPLIES
    Cos(n)(X) << Cos(n)(Y)

  %%% The next function translates

  Sin(n)(X) : Interval =
    LET Xpos    = Intersection(X,[|0,ub(X)|]),
     Xneg    = Intersection(X,[|lb(X),0|]),
CosXpos = Cos(n)(Add(Xpos,[|-pi_ubn(n)/2,-pi_lbn(n)/2|])),
CosXneg = Neg(Cos(n)(Add(Neg(Xneg),[|-pi_ubn(n)/2,-pi_lbn(n)/2|])))
    IN  IF Proper?(Xpos) AND Proper?(Xneg) THEN
              Union(CosXpos,CosXneg)
ELSIF Proper?(Xpos) THEN CosXpos
ELSIF Proper?(Xneg) THEN CosXneg
ELSE [| 1, 0 |] ENDIF

  Sin_fundamental: LEMMA
    Proper?(X) AND
    X << Y IMPLIES
    Sin(n)(X) << Sin(n)(Y)

  tan_0_pi2(n)(X) : Interval =
    let cos_ub_lb = cos_ub(lb(X),n) in
    let cos_lb_ub = cos_lb(ub(X),n) in
    if cos_ub_lb > 0 AND cos_lb_ub > 0 then
      [|sin_lb(lb(X),n)/cos_ub_lb,sin_ub(ub(X),n)/cos_lb_ub|]
    else
      EmptyInterval
    endif

  tan_npi2_pi2(n)(X) : Interval =
    let cos_lb_lb = cos_lb(lb(X),n) in
    let cos_lb_ub = cos_lb(ub(X),n) in
    if cos_lb_lb > 0 AND cos_lb_ub > 0 then
      [|sin_lb(lb(X),n)/cos_lb_lb,sin_ub(ub(X),n)/cos_lb_ub|]
    else
      EmptyInterval
    endif

  tan_npi2_pi2_union: LEMMA
    n>=5 AND
    0 ## X AND X << [|-pi_lb_est(n)/2,pi_lb_est(n)/2|]
    IMPLIES
    tan_npi2_pi2(n)(X) =
    Union(Neg(tan_0_pi2(n)(Neg(Intersection(X,[|-pi_lb_est(n)/2,0|])))),
   tan_0_pi2(n)(Intersection(X,[|0,pi_lb_est(n)/2|])))

  % Approximation to guarantee cos_lb > 0
  Cos_pos_n : MACRO posnat = 5

  Tan(n)(X) : Interval =
    let n = n+Cos_pos_n in
    if    X << [|0,pi_lb_est(n)/2|]        then  tan_0_pi2(n)(X)
    elsif X << [|-pi_lb_est(n)/2,0|]       then  Neg(tan_0_pi2(n)(Neg(X)))
    elsif X << [|-pi_lb_est(n)/2,pi_lb_est(n)/2|] then  tan_npi2_pi2(n)(X)
    else  EmptyInterval
    endif

  Tan_proper: LEMMA
    Proper?(X) AND X << [|-pi_lb_est(n+Cos_pos_n)/2,pi_lb_est(n+Cos_pos_n)/2|]
    IMPLIES
    Proper?(Tan(n)(X))

  Atan(n)(X) : Interval =
    [|atan_lb(lb(X),n),atan_ub(ub(X),n)|]

  Atan_fundamental: LEMMA
    X << Y IMPLIES
    Atan(n)(X) << Atan(n)(Y)

  % lemmas

  Pi_inclusion : LEMMA
    pi ## Pi(n)

  Pi_proper : JUDGEMENT Pi(n) HAS_TYPE ProperInterval

  sin_npi2_pi2 : LEMMA
    X << [|-pi_lbn(n)/2,pi_lbn(n)/2|] AND
    x ## X
    IMPLIES
    sin(x) ## sin_npi2_pi2(n)(X)

  sin_pi2_pi : LEMMA
    X << [|pi_ubn(n)/2,pi_lbn(n)|] AND
    x ## X
    IMPLIES
    sin(x) ## sin_pi2_pi(n)(X)

  sin_0_pi : LEMMA
    X << [|0,pi_lbn(n)|] AND
    x ## X
    IMPLIES
    sin(x) ## sin_0_pi(n)(X)

  sin_npi_0 : LEMMA
    X << [|-pi_lbn(n),0|] AND
    x ## X IMPLIES
    sin(x) ## Neg(sin_0_pi(n)(Neg(X)))

  sin_npi_npi2 : LEMMA
    X << [|-pi_lbn(n),-pi_ubn(n)/2|] AND
    x ## X
    IMPLIES
    sin(x) ## Neg(sin_pi2_pi(n)(Neg(X)))

  cos_0_pi : LEMMA
    X << [|0,pi_lbn(n)|] AND
    x ## X IMPLIES
    cos(x) ## cos_0_pi(n)(X)

  cos_npi_0 : LEMMA
    X << [|-pi_lbn(n),0|] AND
    x ## X IMPLIES
    cos(x) ## cos_0_pi(n)(Neg(X))

  cos_npi2_pi2 : LEMMA
    X << [|-pi_lbn(n)/2,pi_lbn(n)/2|] AND
    x ## X IMPLIES
    cos(x) ## cos_npi2_pi2(n)(X)

  Cos_inclusion : LEMMA
     x ## X IMPLIES
     cos(x) ## Cos(n)(X)

  Sin_inclusion : LEMMA
     x  ## X
     IMPLIES
     sin(x) ## Sin(n)(X)

  Tan_pi2_def : LEMMA
    x ## X AND
    X << [| -pi_lbn(n)/2, pi_lbn(n)/2 |]
    IMPLIES
      Tan?(x)

  cos_lb_gt_0_pos : LEMMA
    x ## [|0,pi_lbn(n)/2|] AND
    n >= Cos_pos_n IMPLIES
    cos_lb(x,n) > 0

  cos_lb_gt_0 : LEMMA
    x ## [|-pi_lbn(n)/2,pi_lbn(n)/2|] AND
    n >= Cos_pos_n IMPLIES
    cos_lb(x,n) > 0

  cos_ub_gt_0 : LEMMA
    x ## [|-pi_lbn(n)/2,pi_lbn(n)/2|] AND
    cos_lb(x,n) > 0 IMPLIES
    cos_ub(x,n) > 0

  cos_lb_ub_gt_0 : LEMMA
    X << [|-pi_lbn(n)/2,pi_lbn(n)/2|] AND
    Proper?(X) AND
    n >= Cos_pos_n  IMPLIES
    cos_lb(lb(X),n) > 0 AND
    cos_lb(ub(X),n) > 0 AND
    cos_ub(lb(X),n) > 0 AND
    cos_ub(ub(X),n) > 0

  tan_0_pi2 : LEMMA
    X << [|0,pi_lbn(n)/2|] AND
    n >= Cos_pos_n AND
    x ## X IMPLIES
    tan(x) ## tan_0_pi2(n)(X)

  tan_npi2_0 : LEMMA
    X << [|-pi_lbn(n)/2,0|] AND
    n >= Cos_pos_n AND
    x ## X IMPLIES
    tan(x) ## Neg(tan_0_pi2(n)(Neg(X)))

  tan_npi2_pi2 : LEMMA
    X << [|-pi_lbn(n)/2,pi_lbn(n)/2|] AND
    Zeroin?(X) AND
    n >= Cos_pos_n AND
    x ## X IMPLIES
    tan(x) ## tan_npi2_pi2(n)(X)

  TAN?(n)(X) : bool =
    X << [| -pi_lb_est(n+Cos_pos_n)/2, pi_lb_est(n+Cos_pos_n)/2 |]

  TAN_Tan : LEMMA
    TAN?(n)(X) AND
    x ## X IMPLIES
      Tan?(x)

  Tan_inclusion : LEMMA
    TAN?(n)(X) AND
    x ## X IMPLIES
    tan(x) ## Tan(n)(X)

  Tan_fundamental: LEMMA
    Proper?(X) AND TAN?(n)(Y) AND
    X << Y IMPLIES
    Tan(n)(X) << Tan(n)(Y)

  Atan_inclusion : LEMMA
    x ## X IMPLIES
    atan(x) ## Atan(n)(X)

  Strict_Tan : LEMMA
    TAN?(n)(X) AND
    StrictInterval?(X) IMPLIES
    StrictInterval?(Tan(n)(X))

  %% Safe version of trigonometric functions
  IMPORTING safe_arith

  safe_Sin(n) : [Interval->Interval] = Safe1(Sin(n))
  safe_Cos(n) : [Interval->Interval] = Safe1(Cos(n))
  safe_Tan(n) : [Interval->Interval] = Safe1(TAN?(n),Tan(n))
  safe_Atan(n) : [Interval->Interval] = Safe1(Atan(n))

  %% Proper version of trigonometric functions
  IMPORTING proper_arith

  Xp   : VAR ProperInterval

  Proper_Sin : JUDGEMENT
    Sin(n)(Xp) HAS_TYPE ProperInterval

  Proper_Cos : JUDGEMENT
    Cos(n)(Xp) HAS_TYPE ProperInterval

  Proper_Tan : JUDGEMENT
    Tan(n)(Xp|TAN?(n)(Xp)) HAS_TYPE ProperInterval

  Proper_Atan : JUDGEMENT
    Atan(n)(Xp) HAS_TYPE ProperInterval

  proper_Sin(n)(Xp): ProperInterval =
    Sin(n)(Xp)

  proper_Cos(n)(Xp): ProperInterval =
    Cos(n)(Xp)

  proper_Tan(n)(Xp|TAN?(n)(Xp)): ProperInterval =
    Tan(n)(Xp)

  proper_Atan(n)(Xp): ProperInterval =
    Atan(n)(Xp)

END interval_trig

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