1 (* Basic interval arithmetic for approximation of constants *)
2 needs "tame/tame_defs.hl";;
3 needs "tame/TameGeneral.hl";;
5 module Constants_approx = struct
7 let interval_arith = new_definition `interval_arith (x:real) (lo, hi) <=> lo <= x /\ x <= hi`;;
10 let CONST_INTERVAL = prove(`!x. interval_arith x (x,x)`, REWRITE_TAC[interval_arith; REAL_LE_REFL]);;
13 let EPS_TO_INTERVAL = prove(`abs (f - x) <= e <=> interval_arith f (x - e, x + e)`,
14 REWRITE_TAC[interval_arith] THEN REAL_ARITH_TAC);;
17 let APPROX_INTERVAL = prove(`(a <= lo /\ hi <= b) /\ interval_arith x (lo, hi)
18 ==> interval_arith x (a,b)`,
19 REWRITE_TAC[interval_arith] THEN REAL_ARITH_TAC);;
23 (* Numerical approximations for cos and acos *)
26 let COS_EQ_NEG_SIN = prove(`!x. cos (x + pi / &2) = --sin x`,
27 REWRITE_TAC[COS_SIN; REAL_ARITH `a - (b + a) = --b`; SIN_NEG]);;
32 let COS_DERIVATIVES = prove(`!x n. ((\x. cos (x + &n * pi / &2)) has_real_derivative cos (x + &(n + 1) * pi / &2)) (atreal x)`,
33 REPEAT GEN_TAC THEN REWRITE_TAC[] THEN
34 MP_TAC (REAL_DIFF_CONV `((\x. cos (x + &n * pi / &2)) has_real_derivative f) (atreal x)`) THEN
35 SUBGOAL_THEN `(&1 + &0) * --sin (x + &n * pi / &2) = cos (x + &(n + 1) * pi / &2)` (fun th -> REWRITE_TAC[th]) THEN
36 REWRITE_TAC[REAL_ARITH `(&1 + &0) * --a = --a`] THEN
37 REWRITE_TAC[GSYM REAL_OF_NUM_ADD] THEN
38 REWRITE_TAC[REAL_ARITH `x + (a + &1) * t = (x + a * t) + t`] THEN
39 REWRITE_TAC[COS_EQ_NEG_SIN]);;
44 let REAL_TAYLOR_COS_RAW = prove(`!x n. abs (cos x - sum (0..n) (\k. if (EVEN k) then ((-- &1) pow (k DIV 2) * x pow k) / &(FACT k) else &0)) <=
45 abs x pow (n + 1) / &(FACT (n + 1))`,
47 MP_TAC (SPECL [`(\i x. cos (x + &i * pi / &2))`; `n:num`; `UNIV:real->bool`; `&1`] REAL_TAYLOR) THEN
50 REWRITE_TAC[is_realinterval; IN_UNIV; WITHINREAL_UNIV; COS_DERIVATIVES; COS_BOUND];
53 REWRITE_TAC[IN_UNIV] THEN
54 DISCH_THEN (MP_TAC o SPECL [`&0`; `x:real`]) THEN
55 REWRITE_TAC[REAL_MUL_LZERO; REAL_ADD_RID; REAL_ADD_LID; REAL_SUB_RZERO; REAL_MUL_LID] THEN
56 SUBGOAL_THEN `!i. cos (&i * pi / &2) * x pow i / &(FACT i) = if EVEN i then (-- &1 pow (i DIV 2) * x pow i) / &(FACT i) else &0` (fun th -> SIMP_TAC[th]) THEN
58 ASM_CASES_TAC `EVEN i` THEN ASM_REWRITE_TAC[] THENL
61 REWRITE_TAC[EVEN_EXISTS] THEN
62 STRIP_TAC THEN ASM_REWRITE_TAC[] THEN
63 SUBGOAL_THEN `(2 * m) DIV 2 = m` (fun th -> REWRITE_TAC[th]) THENL
65 MATCH_MP_TAC DIV_MULT THEN
69 REWRITE_TAC[GSYM REAL_OF_NUM_MUL] THEN
70 REWRITE_TAC[REAL_ARITH `(&2 * a) * b / &2 = a * b`] THEN
71 REWRITE_TAC[COS_NPI] THEN
75 SUBGOAL_THEN `cos (&i * pi / &2) = &0` (fun th -> REWRITE_TAC[th]) THENL
77 REWRITE_TAC[COS_ZERO] THEN
78 DISJ1_TAC THEN EXISTS_TAC `i:num` THEN
82 REWRITE_TAC[REAL_MUL_LZERO]);;
85 let SUM_PAIR_0 = prove(`!f n. sum (0..2 * n + 1) f = sum(0..n) (\i. f (2 * i) + f (2 * i + 1))`,
87 MP_TAC (SPECL [`f:num->real`; `0`; `n:num`] SUM_PAIR) THEN
88 REWRITE_TAC[ARITH_RULE `2 * 0 = 0`]);;
91 let REAL_TAYLOR_COS = prove(`!x n. abs (cos x - sum (0..n) (\i. (-- &1) pow i * x pow (2 * i) / &(FACT (2 * i)))) <= abs x pow (2*n + 2) / &(FACT (2*n + 2))`,
93 MP_TAC (SPECL [`x:real`; `2 * n + 1`] REAL_TAYLOR_COS_RAW) THEN
94 REWRITE_TAC[SUM_PAIR_0; EVEN_DOUBLE; ARITH_RULE `(2 * n + 1) + 1 = 2 *n + 2`] THEN
95 SUBGOAL_THEN `!i. ~(EVEN (2 * i + 1))` MP_TAC THENL
97 GEN_TAC THEN REWRITE_TAC[NOT_EVEN] THEN
98 REWRITE_TAC[ARITH_ODD; ODD_ADD; ODD_MULT];
101 DISCH_THEN (fun th -> SIMP_TAC[th]) THEN
102 SUBGOAL_THEN `!i. (2 * i) DIV 2 = i` MP_TAC THENL
105 MATCH_MP_TAC DIV_MULT THEN
109 DISCH_THEN (fun th -> REWRITE_TAC[th; REAL_ADD_RID]) THEN
110 REWRITE_TAC[REAL_ARITH `(a * b) / c = a * b / c`]);;
118 let tm = list_mk_comb (`sum:(num->bool)->(num->real)->real`, [mk_comb (`(..) 0`, mk_small_numeral n); `f:num->real`]) in
119 let suc_th = REWRITE_RULE[EQ_CLAUSES] (REWRITE_CONV[ARITH] (mk_eq (mk_small_numeral n, mk_comb (`SUC`, mk_small_numeral (n - 1))))) in
120 let th1 = REWRITE_CONV[suc_th] tm in
121 REWRITE_RULE[SUM_CLAUSES_NUMSEG; ARITH] th1 in
122 let rec rewriter th n =
124 rewriter (REWRITE_RULE[SUM_lemma n; GSYM REAL_ADD_ASSOC] th) (n - 1)
127 GEN_ALL (rewriter (SUM_lemma n) (n - 1));;
130 (* Evaluates cos at a given point using n terms from the cosine Taylor series *)
132 let th1 = (SPECL [x; mk_small_numeral n] REAL_TAYLOR_COS) in
133 let th2 = REWRITE_RULE[gen_sum_thm n] th1 in
134 let th4 = CONV_RULE (NUM_REDUCE_CONV) th2 in
135 let th5 = CONV_RULE (DEPTH_CONV REAL_INT_POW_CONV) th4 in
136 CONV_RULE (REAL_RAT_REDUCE_CONV) th5;;
140 let acs3_lo = prove(`#1.230959417 <= acs (&1 / &3)`,
141 SUBGOAL_THEN `#1.230959417 = acs (cos(#1.230959417))` (fun th -> ONCE_REWRITE_TAC[th]) THENL
143 MATCH_MP_TAC (GSYM ACS_COS) THEN
144 MP_TAC PI_APPROX_32 THEN
148 MATCH_MP_TAC ACS_MONO_LE THEN
149 REWRITE_TAC[COS_BOUNDS] THEN
150 MP_TAC (cos_eval `#1.230959417` 6) THEN
154 (* 1.23095941734077 *)
155 let acs3_hi = prove(`acs(&1 / &3) <= #1.230959418`,
156 SUBGOAL_THEN `#1.230959418 = acs(cos(#1.230959418))` (fun th -> ONCE_REWRITE_TAC[th]) THENL
158 MATCH_MP_TAC (GSYM ACS_COS) THEN
159 MP_TAC PI_APPROX_32 THEN
163 MATCH_MP_TAC ACS_MONO_LE THEN
164 REWRITE_TAC[COS_BOUNDS] THEN
165 MP_TAC (cos_eval `#1.230959418` 6) THEN
169 let le_op_real = `(<=):real->real->bool` and
170 minus_op_real = `(-):real->real->real` and
171 plus_op_real = `(+):real->real->real` and
172 mul_op_real = `( * ):real->real->real` and
173 div_op_real = `(/):real->real->real` and
174 inv_op_real = `inv:real->real` and
175 neg_op_real = `(--):real->real`;;
178 let tm = mk_comb(mk_comb(`DECIMAL`, mk_numeral (Num.abs_num a)), mk_numeral b) in
180 mk_comb (neg_op_real, tm)
186 let approx_interval th precision =
187 let th' = CONV_RULE (RAND_CONV (REWRITE_CONV[DECIMAL] THENC REAL_RAT_REDUCE_CONV)) th in
188 let lo_tm, hi_tm = dest_pair (rand(concl th')) in
189 let lo, hi = rat_of_term lo_tm, rat_of_term hi_tm in
190 let m = (Int 10 **/ Int precision) in
191 let lo_bound = floor_num (lo */ m) in
192 let hi_bound = ceiling_num (hi */ m) in
193 let conv = EQT_ELIM o REAL_RAT_LE_CONV in
194 let lo_th = conv (mk_binop le_op_real (mk_decimal lo_bound m) lo_tm) in
195 let hi_th = conv (mk_binop le_op_real hi_tm (mk_decimal hi_bound m)) in
196 let th0 = CONJ (CONJ lo_th hi_th) th' in
197 MATCH_MP APPROX_INTERVAL th0;;
202 approx_interval th1 9;;
204 let th = cos_eval `#0.61547970867` 5;;
205 let th1 = (CONV_RULE REAL_RAT_REDUCE_CONV) (REWRITE_RULE[EPS_TO_INTERVAL] th);;
206 float_of_num (rat_of_term (rand(concl th)));;
208 approx_interval (concl th1) 10;;
213 (************************************)
218 let INTERVAL_SQRT = prove(`interval_arith x (a, b) /\
219 (c * c <= a /\ b <= d * d) ==>
220 interval_arith (sqrt x) (abs c, abs d)`,
221 REWRITE_TAC[interval_arith] THEN REPEAT STRIP_TAC THENL
223 MATCH_MP_TAC REAL_LE_RSQRT THEN
224 MATCH_MP_TAC REAL_LE_TRANS THEN
225 EXISTS_TAC `a:real` THEN
226 ASM_REWRITE_TAC[REAL_ARITH `abs a pow 2 = a * a`];
227 MATCH_MP_TAC REAL_LE_LSQRT THEN
228 ASM_REWRITE_TAC[REAL_ARITH `abs d pow 2 = d * d`; REAL_ABS_POS] THEN
231 MATCH_MP_TAC REAL_LE_TRANS THEN
232 EXISTS_TAC `a:real` THEN
233 ASM_REWRITE_TAC[] THEN
234 MATCH_MP_TAC REAL_LE_TRANS THEN
235 EXISTS_TAC `c * c:real` THEN
236 ASM_REWRITE_TAC[REAL_LE_SQUARE];
237 MATCH_MP_TAC REAL_LE_TRANS THEN
238 EXISTS_TAC `b:real` THEN
245 let interval_sqrt th precision =
246 let th' = CONV_RULE (REWRITE_CONV[DECIMAL] THENC REAL_RAT_REDUCE_CONV) th in
247 let lo, hi = dest_pair(rand(concl th')) in
248 let x_lo, x_hi = float_of_num (rat_of_term lo), float_of_num (rat_of_term hi) in
249 let lo_sqrt, hi_sqrt = Pervasives.sqrt x_lo, Pervasives.sqrt x_hi in
250 let m = 10.0 ** float_of_int precision in
251 let hack n = num_of_string (Int64.to_string (Int64.of_float n)) in
252 let sqrt_lo_num, sqrt_hi_num = hack (floor (lo_sqrt *. m)), hack (ceil (hi_sqrt *. m)) in
253 let m_num = Int 10 **/ Int precision in
254 let x_lo_tm = mk_decimal sqrt_lo_num m_num in
255 let x_hi_tm = mk_decimal sqrt_hi_num m_num in
256 let conv = EQT_ELIM o REAL_RAT_REDUCE_CONV in
257 let lo_th = conv (mk_binop le_op_real (mk_binop mul_op_real x_lo_tm x_lo_tm) lo) in
258 let hi_th = conv (mk_binop le_op_real hi (mk_binop mul_op_real x_hi_tm x_hi_tm)) in
259 let th0 = CONJ th' (CONJ lo_th hi_th) in
260 (CONV_RULE REAL_RAT_REDUCE_CONV) (MATCH_MP INTERVAL_SQRT th0);;
264 (************************************)
266 (* Arithmetic of intervals *)
268 let INTERVAL_ADD = prove(`interval_arith x (a, b) /\ interval_arith y (c, d)
269 ==> interval_arith (x + y) (a + c, b + d)`,
270 REWRITE_TAC[interval_arith] THEN REAL_ARITH_TAC);;
273 let INTERVAL_SUB = prove(`interval_arith x (a, b) /\ interval_arith y (c, d)
274 ==> interval_arith (x - y) (a - d, b - c)`,
275 REWRITE_TAC[interval_arith] THEN REAL_ARITH_TAC);;
278 let INTERVAL_NEG = prove(`interval_arith x (a, b) ==>
279 interval_arith (--x) (--b, --a)`,
280 REWRITE_TAC[interval_arith] THEN REAL_ARITH_TAC);;
284 let INTERVAL_INV = prove(`interval_arith x (a, b) /\ (&0 < a \/ b < &0)
285 ==> interval_arith (inv x) (inv b, inv a)`,
286 REWRITE_TAC[interval_arith] THEN
289 CONJ_TAC THEN MATCH_MP_TAC REAL_LE_INV2 THEN
290 ASM_REWRITE_TAC[] THEN
291 REPEAT (POP_ASSUM MP_TAC) THEN
295 ONCE_REWRITE_TAC[REAL_ARITH `a <= b <=> --b <= --a`] THEN
296 REWRITE_TAC[GSYM REAL_INV_NEG] THEN
297 CONJ_TAC THEN MATCH_MP_TAC REAL_LE_INV2 THEN
298 REPEAT (POP_ASSUM MP_TAC) THEN
302 let INTERVAL_INV_POS = prove(`interval_arith x (a,b) /\ &0 < a
303 ==> interval_arith (inv x) (inv b, inv a)`,
304 SIMP_TAC[INTERVAL_INV]);;
307 let INTERVAL_INV_NEG = prove(`interval_arith x (a,b) /\ b < &0
308 ==> interval_arith (inv x) (inv b, inv a)`,
309 SIMP_TAC[INTERVAL_INV]);;
313 let INTERVAL_MUL_lemma = prove(`!x y a b c d. interval_arith x (a, b) /\ interval_arith y (c, d) /\ x <= y
314 ==> x * y <= max (max (a * c) (a * d)) (max (b * c) (b * d))`,
316 REWRITE_TAC[interval_arith] THEN DISCH_TAC THEN
317 ABBREV_TAC `t = max (max (a * c) (a * d)) (max (b * c) (b * d))` THEN
318 SUBGOAL_THEN `a * c <= t /\ a * d <= t /\ b * c <= t /\ b * d <= t:real` ASSUME_TAC THENL
325 DISJ_CASES_TAC (REAL_ARITH `&0 <= x \/ x <= &0`) THENL
327 MATCH_MP_TAC REAL_LE_TRANS THEN
328 EXISTS_TAC `b * d:real` THEN
329 ASM_REWRITE_TAC[] THEN
330 MATCH_MP_TAC REAL_LE_MUL2 THEN
331 ASM_REWRITE_TAC[] THEN
332 MATCH_MP_TAC REAL_LE_TRANS THEN
333 EXISTS_TAC `x:real` THEN
338 DISJ_CASES_TAC (REAL_ARITH `&0 <= b \/ b <= &0`) THENL
340 DISJ_CASES_TAC (REAL_ARITH `&0 <= y \/ y <= &0`) THENL
342 MATCH_MP_TAC REAL_LE_TRANS THEN
346 ONCE_REWRITE_TAC[REAL_ARITH `&0 = &0 * y`] THEN
347 MATCH_MP_TAC REAL_LE_RMUL THEN
352 MATCH_MP_TAC REAL_LE_TRANS THEN
353 EXISTS_TAC `b * d:real` THEN
354 ASM_REWRITE_TAC[] THEN
355 MATCH_MP_TAC REAL_LE_MUL THEN
356 ASM_REWRITE_TAC[] THEN
357 MATCH_MP_TAC REAL_LE_TRANS THEN
358 EXISTS_TAC `y:real` THEN
363 MATCH_MP_TAC REAL_LE_TRANS THEN
364 EXISTS_TAC `a * c:real` THEN
365 ASM_REWRITE_TAC[] THEN
366 ONCE_REWRITE_TAC[GSYM REAL_NEG_MUL2] THEN
367 MATCH_MP_TAC REAL_LE_MUL2 THEN
368 ASM_REWRITE_TAC[REAL_LE_NEG; REAL_NEG_GE0];
372 DISJ_CASES_TAC (REAL_ARITH `&0 <= c \/ c <= &0`) THENL
374 MATCH_MP_TAC REAL_LE_TRANS THEN
375 EXISTS_TAC `b * c:real` THEN
376 ASM_REWRITE_TAC[] THEN
377 ONCE_REWRITE_TAC[REAL_ARITH `x * y <= b * c <=> (--b) * c <= (--x) * y`] THEN
378 MATCH_MP_TAC REAL_LE_MUL2 THEN
379 ASM_REWRITE_TAC[REAL_LE_NEG; REAL_NEG_GE0];
383 DISJ_CASES_TAC (REAL_ARITH `&0 <= y \/ y <= &0`) THENL
385 MATCH_MP_TAC REAL_LE_TRANS THEN
389 ONCE_REWRITE_TAC[REAL_ARITH `&0 = &0 * y`] THEN
390 MATCH_MP_TAC REAL_LE_RMUL THEN
395 MATCH_MP_TAC REAL_LE_TRANS THEN
396 EXISTS_TAC `a * c:real` THEN
397 ASM_REWRITE_TAC[] THEN
398 ONCE_REWRITE_TAC[GSYM REAL_NEG_MUL2] THEN
399 MATCH_MP_TAC REAL_LE_MUL THEN
400 ASM_REWRITE_TAC[REAL_NEG_GE0] THEN
401 MATCH_MP_TAC REAL_LE_TRANS THEN
402 EXISTS_TAC `x:real` THEN
407 MATCH_MP_TAC REAL_LE_TRANS THEN
408 EXISTS_TAC `a * c:real` THEN
409 ASM_REWRITE_TAC[] THEN
410 ONCE_REWRITE_TAC[GSYM REAL_NEG_MUL2] THEN
411 MATCH_MP_TAC REAL_LE_MUL2 THEN
412 ASM_REWRITE_TAC[REAL_LE_NEG; REAL_NEG_GE0]);;
416 let INTERVAL_MUL_lemma2 = prove(`!x y a b c d. interval_arith x (a,b) /\ interval_arith y (c,d)
417 ==> x * y <= max (max (a * c) (a * d)) (max (b * c) (b * d))`,
418 REPEAT STRIP_TAC THEN
419 DISJ_CASES_TAC (REAL_ARITH `x <= y \/ y <= x:real`) THENL
421 MATCH_MP_TAC INTERVAL_MUL_lemma THEN
426 MP_TAC (SPECL [`y:real`; `x:real`; `c:real`; `d:real`; `a:real`; `b:real`] INTERVAL_MUL_lemma) THEN
427 ASM_REWRITE_TAC[] THEN
433 let INTERVAL_MUL = prove(`interval_arith x (a, b) /\ interval_arith y (c, d)
434 ==> interval_arith (x * y)
435 (min (min (a * c) (a * d)) (min (b * c) (b * d)),
436 max (max (a * c) (a * d)) (max (b * c) (b * d)))`,
437 DISCH_TAC THEN REWRITE_TAC[interval_arith] THEN
438 ASM_SIMP_TAC[INTERVAL_MUL_lemma2] THEN
439 MP_TAC (SPECL[`--x:real`; `y:real`; `--b:real`; `--a:real`; `c:real`; `d:real`] INTERVAL_MUL_lemma2) THEN
440 ASM_SIMP_TAC[INTERVAL_NEG] THEN
448 (**************************************)
451 let const_interval tm = SPEC tm CONST_INTERVAL;;
454 let interval_neg th = MATCH_MP INTERVAL_NEG th;;
457 let interval_add th1 th2 =
458 let th0 = MATCH_MP INTERVAL_ADD (CONJ th1 th2) in
459 (CONV_RULE (RAND_CONV REAL_RAT_REDUCE_CONV)) th0;;
461 let interval_sub th1 th2 =
462 let th0 = MATCH_MP INTERVAL_SUB (CONJ th1 th2) in
463 (CONV_RULE (RAND_CONV REAL_RAT_REDUCE_CONV)) th0;;
466 let interval_mul th1 th2 =
467 let th0 = MATCH_MP INTERVAL_MUL (CONJ th1 th2) in
468 (CONV_RULE (RAND_CONV REAL_RAT_REDUCE_CONV)) th0;;
471 let interval_inv th =
472 let lt_op_real = `(<):real->real->bool` in
473 let lo_tm, hi_tm = dest_pair(rand(concl th)) in
474 let lo_ineq = REAL_RAT_LT_CONV (mk_binop lt_op_real `&0` lo_tm) in
475 if (rand(concl lo_ineq) = `T`) then
476 let th0 = CONJ th (EQT_ELIM lo_ineq) in
477 (CONV_RULE (RAND_CONV REAL_RAT_REDUCE_CONV)) (MATCH_MP INTERVAL_INV_POS th0)
479 let hi_ineq = REAL_RAT_LT_CONV (mk_binop lt_op_real hi_tm `&0`) in
480 if (rand(concl hi_ineq) = `T`) then
481 let th0 = CONJ th (EQT_ELIM hi_ineq) in
482 (CONV_RULE (RAND_CONV REAL_RAT_REDUCE_CONV)) (MATCH_MP INTERVAL_INV_NEG th0)
483 else failwith("interval_inv: 0 is inside interval");;
485 let interval_div th1 th2 =
486 let th2' = interval_inv th2 in
487 ONCE_REWRITE_RULE[GSYM real_div] (interval_mul th1 th2');;
491 (*************************)
494 let acs3_interval = REWRITE_RULE[GSYM interval_arith] (CONJ acs3_lo acs3_hi);;
497 let pi_interval = prove(`interval_arith pi (#3.141592653, #3.141592654)`,
498 REWRITE_TAC[interval_arith] THEN
499 MP_TAC PI_APPROX_32 THEN REAL_ARITH_TAC);;
502 let tgt_interval = prove(`interval_arith tgt (#1.541, #1.541)`,
503 REWRITE_TAC[Tame_defs.tgt; interval_arith; REAL_LE_REFL]);;
507 let interval_table = Hashtbl.create 10;;
508 let add_interval th = Hashtbl.add interval_table ((rand o rator o concl) th) th;;
512 let rec create_interval tm =
513 if Hashtbl.mem interval_table tm then
514 Hashtbl.find interval_table tm
516 if (is_ratconst tm) then
518 else if (is_binop plus_op_real tm) then
519 let lhs, rhs = dest_binop plus_op_real tm in
520 interval_add (create_interval lhs) (create_interval rhs)
521 else if (is_binop minus_op_real tm) then
522 let lhs, rhs = dest_binop minus_op_real tm in
523 interval_sub (create_interval lhs) (create_interval rhs)
524 else if (is_binop mul_op_real tm) then
525 let lhs, rhs = dest_binop mul_op_real tm in
526 interval_mul (create_interval lhs) (create_interval rhs)
527 else if (is_binop div_op_real tm) then
528 let lhs, rhs = dest_binop div_op_real tm in
529 interval_div (create_interval lhs) (create_interval rhs)
530 else if (is_comb tm) then
531 let ltm, rtm = dest_comb tm in
532 if (ltm = inv_op_real) then
533 interval_inv (create_interval rtm)
534 else if (ltm = neg_op_real) then
535 interval_neg (create_interval rtm)
536 else failwith "create_interval: unknown unary operation"
538 failwith "create_interval: unexpected term";;
545 add_interval pi_interval;;
546 add_interval acs3_interval;;
547 add_interval tgt_interval;;
548 add_interval (REWRITE_RULE[GSYM sqrt8] (interval_sqrt (const_interval `&8`) 9));;
549 add_interval (REWRITE_RULE[GSYM sol0] (create_interval `&3 * acs(&1 / &3) - pi`));;
550 add_interval (create_interval `sol0 / pi`);;
552 let rho218 = new_definition `rho218 = rho(#2.18)`;;
554 let rho218_def = (REWRITE_CONV[rho218; rho; ly; interp; GSYM Tame_general.sol0_over_pi_EQ_const1] THENC
555 REAL_RAT_REDUCE_CONV) `rho218`;;
557 let rho218_interval = REWRITE_RULE[SYM rho218_def] (create_interval(rand(concl rho218_def)));;
559 add_interval rho218_interval;;
563 approx_interval (create_interval `rho (#2.18)`) 8;;
565 approx_interval (create_interval `&2 * (pi + sol0)`) 6;;
567 approx_interval (create_interval `sqrt8 - pi / sol0 + rho(#2.18) * &3`) 6;;
569 approx_interval (create_interval `pi * pi`) 6;;