src/HOL/Real_Asymp/Real_Asymp_Examples.thy
changeset 70817 dd675800469d
parent 69597 ff784d5a5bfb
equal deleted inserted replaced
70816:5bc338cee4a0 70817:dd675800469d
   436   have "(\<lambda>n. log 2 (real ((n + 3) choose 3) / 4) + 1) =
   436   have "(\<lambda>n. log 2 (real ((n + 3) choose 3) / 4) + 1) =
   437           (\<lambda>n. log 2 ((real n + 1) * (real n + 2) * (real n + 3) / 24) + 1)"
   437           (\<lambda>n. log 2 ((real n + 1) * (real n + 2) * (real n + 3) / 24) + 1)"
   438     by (subst binomial_gbinomial) 
   438     by (subst binomial_gbinomial) 
   439        (simp add: gbinomial_pochhammer' numeral_3_eq_3 pochhammer_Suc add_ac)
   439        (simp add: gbinomial_pochhammer' numeral_3_eq_3 pochhammer_Suc add_ac)
   440   moreover have "\<dots> \<sim> (\<lambda>n. 3 / ln 2 * ln n)"
   440   moreover have "\<dots> \<sim> (\<lambda>n. 3 / ln 2 * ln n)"
   441     by (real_asymp simp: divide_simps)
   441     by (real_asymp simp: field_split_simps)
   442   ultimately show ?thesis by simp
   442   ultimately show ?thesis by simp
   443 qed
   443 qed
   444 
   444 
   445 end
   445 end
   446 
   446 
   485   
   485   
   486 lemma "eventually (\<lambda>x::real. 1 / x^2 \<ge> 1 / x) (at_left 0)"
   486 lemma "eventually (\<lambda>x::real. 1 / x^2 \<ge> 1 / x) (at_left 0)"
   487   by real_asymp
   487   by real_asymp
   488 
   488 
   489 lemma "A > 1 \<Longrightarrow> (\<lambda>n. ((1 + 1 / sqrt A) / 2) powr real_of_int (2 ^ Suc n)) \<longlonglongrightarrow> 0"
   489 lemma "A > 1 \<Longrightarrow> (\<lambda>n. ((1 + 1 / sqrt A) / 2) powr real_of_int (2 ^ Suc n)) \<longlonglongrightarrow> 0"
   490   by (real_asymp simp: divide_simps add_pos_pos)  
   490   by (real_asymp simp: field_split_simps add_pos_pos)  
   491 
   491 
   492 lemma 
   492 lemma 
   493   assumes "c > (1 :: real)" "k \<noteq> 0"
   493   assumes "c > (1 :: real)" "k \<noteq> 0"
   494   shows   "(\<lambda>n. real n ^ k) \<in> o(\<lambda>n. c ^ n)"
   494   shows   "(\<lambda>n. real n ^ k) \<in> o(\<lambda>n. c ^ n)"
   495   using assms by (real_asymp (verbose))
   495   using assms by (real_asymp (verbose))