equal
deleted
inserted
replaced
1345 next |
1345 next |
1346 assume "\<not> 0 < x" with `x \<noteq> 0` show "isCont ln x" |
1346 assume "\<not> 0 < x" with `x \<noteq> 0` show "isCont ln x" |
1347 unfolding isCont_def |
1347 unfolding isCont_def |
1348 by (subst filterlim_cong[OF _ refl, of _ "nhds (ln 0)" _ "\<lambda>_. ln 0"]) |
1348 by (subst filterlim_cong[OF _ refl, of _ "nhds (ln 0)" _ "\<lambda>_. ln 0"]) |
1349 (auto simp: ln_neg_is_const not_less eventually_at dist_real_def |
1349 (auto simp: ln_neg_is_const not_less eventually_at dist_real_def |
1350 intro!: tendsto_const exI[of _ "\<bar>x\<bar>"]) |
1350 intro!: exI[of _ "\<bar>x\<bar>"]) |
1351 qed |
1351 qed |
1352 |
1352 |
1353 lemma tendsto_ln [tendsto_intros]: |
1353 lemma tendsto_ln [tendsto_intros]: |
1354 "(f ---> a) F \<Longrightarrow> a \<noteq> 0 \<Longrightarrow> ((\<lambda>x. ln (f x)) ---> ln a) F" |
1354 "(f ---> a) F \<Longrightarrow> a \<noteq> 0 \<Longrightarrow> ((\<lambda>x. ln (f x)) ---> ln a) F" |
1355 by (rule isCont_tendsto_compose [OF isCont_ln]) |
1355 by (rule isCont_tendsto_compose [OF isCont_ln]) |
2212 proof (rule filterlim_mono_eventually) |
2212 proof (rule filterlim_mono_eventually) |
2213 show "eventually (\<lambda>xa. exp (ln (1 + x * xa) / xa) = (1 + x * xa) powr (1 / xa)) (at_right 0)" |
2213 show "eventually (\<lambda>xa. exp (ln (1 + x * xa) / xa) = (1 + x * xa) powr (1 / xa)) (at_right 0)" |
2214 unfolding eventually_at_right[OF zero_less_one] |
2214 unfolding eventually_at_right[OF zero_less_one] |
2215 using `x \<noteq> 0` by (intro exI[of _ "1 / \<bar>x\<bar>"]) (auto simp: field_simps powr_def) |
2215 using `x \<noteq> 0` by (intro exI[of _ "1 / \<bar>x\<bar>"]) (auto simp: field_simps powr_def) |
2216 qed (simp_all add: at_eq_sup_left_right) |
2216 qed (simp_all add: at_eq_sup_left_right) |
2217 qed (simp add: tendsto_const) |
2217 qed simp |
2218 |
2218 |
2219 lemma tendsto_exp_limit_at_top: |
2219 lemma tendsto_exp_limit_at_top: |
2220 fixes x :: real |
2220 fixes x :: real |
2221 shows "((\<lambda>y. (1 + x / y) powr y) ---> exp x) at_top" |
2221 shows "((\<lambda>y. (1 + x / y) powr y) ---> exp x) at_top" |
2222 apply (subst filterlim_at_top_to_right) |
2222 apply (subst filterlim_at_top_to_right) |
3731 assumes "\<bar>x\<bar> \<le> 1" |
3731 assumes "\<bar>x\<bar> \<le> 1" |
3732 shows "(\<lambda> n. 1 / real (n*2+1) * x^(n*2+1)) ----> 0" (is "?a ----> 0") |
3732 shows "(\<lambda> n. 1 / real (n*2+1) * x^(n*2+1)) ----> 0" (is "?a ----> 0") |
3733 proof (cases "x = 0") |
3733 proof (cases "x = 0") |
3734 case True |
3734 case True |
3735 thus ?thesis |
3735 thus ?thesis |
3736 unfolding One_nat_def by (auto simp add: tendsto_const) |
3736 unfolding One_nat_def by auto |
3737 next |
3737 next |
3738 case False |
3738 case False |
3739 have "norm x \<le> 1" and "x \<le> 1" and "-1 \<le> x" using assms by auto |
3739 have "norm x \<le> 1" and "x \<le> 1" and "-1 \<le> x" using assms by auto |
3740 show "?a ----> 0" |
3740 show "?a ----> 0" |
3741 proof (cases "\<bar>x\<bar> < 1") |
3741 proof (cases "\<bar>x\<bar> < 1") |