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Mirrors > Home > MPE Home > Th. List > Mathboxes > sqrtcval2 | Structured version Visualization version GIF version |
Description: Explicit formula for the complex square root in terms of the square root of nonnegative reals. The right side is slightly more compact than sqrtcval 41818. (Contributed by RP, 18-May-2024.) |
Ref | Expression |
---|---|
sqrtcval2 | ⊢ (𝐴 ∈ ℂ → (√‘𝐴) = ((√‘(((abs‘𝐴) + (ℜ‘𝐴)) / 2)) + (if((ℑ‘𝐴) < 0, -i, i) · (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2))))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | sqrtcval 41818 | . 2 ⊢ (𝐴 ∈ ℂ → (√‘𝐴) = ((√‘(((abs‘𝐴) + (ℜ‘𝐴)) / 2)) + (i · (if((ℑ‘𝐴) < 0, -1, 1) · (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2)))))) | |
2 | ovif2 7449 | . . . . . . 7 ⊢ (i · if((ℑ‘𝐴) < 0, -1, 1)) = if((ℑ‘𝐴) < 0, (i · -1), (i · 1)) | |
3 | neg1cn 12225 | . . . . . . . . 9 ⊢ -1 ∈ ℂ | |
4 | ax-icn 11068 | . . . . . . . . 9 ⊢ i ∈ ℂ | |
5 | 4 | mulm1i 11558 | . . . . . . . . 9 ⊢ (-1 · i) = -i |
6 | 3, 4, 5 | mulcomli 11122 | . . . . . . . 8 ⊢ (i · -1) = -i |
7 | 4 | mulid1i 11117 | . . . . . . . 8 ⊢ (i · 1) = i |
8 | ifeq12 4502 | . . . . . . . 8 ⊢ (((i · -1) = -i ∧ (i · 1) = i) → if((ℑ‘𝐴) < 0, (i · -1), (i · 1)) = if((ℑ‘𝐴) < 0, -i, i)) | |
9 | 6, 7, 8 | mp2an 690 | . . . . . . 7 ⊢ if((ℑ‘𝐴) < 0, (i · -1), (i · 1)) = if((ℑ‘𝐴) < 0, -i, i) |
10 | 2, 9 | eqtr2i 2765 | . . . . . 6 ⊢ if((ℑ‘𝐴) < 0, -i, i) = (i · if((ℑ‘𝐴) < 0, -1, 1)) |
11 | 10 | a1i 11 | . . . . 5 ⊢ (𝐴 ∈ ℂ → if((ℑ‘𝐴) < 0, -i, i) = (i · if((ℑ‘𝐴) < 0, -1, 1))) |
12 | 11 | oveq1d 7366 | . . . 4 ⊢ (𝐴 ∈ ℂ → (if((ℑ‘𝐴) < 0, -i, i) · (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2))) = ((i · if((ℑ‘𝐴) < 0, -1, 1)) · (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2)))) |
13 | 4 | a1i 11 | . . . . 5 ⊢ (𝐴 ∈ ℂ → i ∈ ℂ) |
14 | neg1rr 12226 | . . . . . . . 8 ⊢ -1 ∈ ℝ | |
15 | 1re 11113 | . . . . . . . 8 ⊢ 1 ∈ ℝ | |
16 | 14, 15 | ifcli 4531 | . . . . . . 7 ⊢ if((ℑ‘𝐴) < 0, -1, 1) ∈ ℝ |
17 | 16 | a1i 11 | . . . . . 6 ⊢ (𝐴 ∈ ℂ → if((ℑ‘𝐴) < 0, -1, 1) ∈ ℝ) |
18 | 17 | recnd 11141 | . . . . 5 ⊢ (𝐴 ∈ ℂ → if((ℑ‘𝐴) < 0, -1, 1) ∈ ℂ) |
19 | sqrtcvallem3 41815 | . . . . . 6 ⊢ (𝐴 ∈ ℂ → (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2)) ∈ ℝ) | |
20 | 19 | recnd 11141 | . . . . 5 ⊢ (𝐴 ∈ ℂ → (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2)) ∈ ℂ) |
21 | 13, 18, 20 | mulassd 11136 | . . . 4 ⊢ (𝐴 ∈ ℂ → ((i · if((ℑ‘𝐴) < 0, -1, 1)) · (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2))) = (i · (if((ℑ‘𝐴) < 0, -1, 1) · (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2))))) |
22 | 12, 21 | eqtrd 2776 | . . 3 ⊢ (𝐴 ∈ ℂ → (if((ℑ‘𝐴) < 0, -i, i) · (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2))) = (i · (if((ℑ‘𝐴) < 0, -1, 1) · (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2))))) |
23 | 22 | oveq2d 7367 | . 2 ⊢ (𝐴 ∈ ℂ → ((√‘(((abs‘𝐴) + (ℜ‘𝐴)) / 2)) + (if((ℑ‘𝐴) < 0, -i, i) · (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2)))) = ((√‘(((abs‘𝐴) + (ℜ‘𝐴)) / 2)) + (i · (if((ℑ‘𝐴) < 0, -1, 1) · (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2)))))) |
24 | 1, 23 | eqtr4d 2779 | 1 ⊢ (𝐴 ∈ ℂ → (√‘𝐴) = ((√‘(((abs‘𝐴) + (ℜ‘𝐴)) / 2)) + (if((ℑ‘𝐴) < 0, -i, i) · (√‘(((abs‘𝐴) − (ℜ‘𝐴)) / 2))))) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 = wceq 1541 ∈ wcel 2106 ifcif 4484 class class class wbr 5103 ‘cfv 6493 (class class class)co 7351 ℂcc 11007 ℝcr 11008 0cc0 11009 1c1 11010 ici 11011 + caddc 11012 · cmul 11014 < clt 11147 − cmin 11343 -cneg 11344 / cdiv 11770 2c2 12166 ℜcre 14936 ℑcim 14937 √csqrt 15072 abscabs 15073 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1913 ax-6 1971 ax-7 2011 ax-8 2108 ax-9 2116 ax-10 2137 ax-11 2154 ax-12 2171 ax-ext 2707 ax-sep 5254 ax-nul 5261 ax-pow 5318 ax-pr 5382 ax-un 7664 ax-cnex 11065 ax-resscn 11066 ax-1cn 11067 ax-icn 11068 ax-addcl 11069 ax-addrcl 11070 ax-mulcl 11071 ax-mulrcl 11072 ax-mulcom 11073 ax-addass 11074 ax-mulass 11075 ax-distr 11076 ax-i2m1 11077 ax-1ne0 11078 ax-1rid 11079 ax-rnegex 11080 ax-rrecex 11081 ax-cnre 11082 ax-pre-lttri 11083 ax-pre-lttrn 11084 ax-pre-ltadd 11085 ax-pre-mulgt0 11086 ax-pre-sup 11087 |
This theorem depends on definitions: df-bi 206 df-an 397 df-or 846 df-3or 1088 df-3an 1089 df-tru 1544 df-fal 1554 df-ex 1782 df-nf 1786 df-sb 2068 df-mo 2538 df-eu 2567 df-clab 2714 df-cleq 2728 df-clel 2814 df-nfc 2887 df-ne 2942 df-nel 3048 df-ral 3063 df-rex 3072 df-rmo 3351 df-reu 3352 df-rab 3406 df-v 3445 df-sbc 3738 df-csb 3854 df-dif 3911 df-un 3913 df-in 3915 df-ss 3925 df-pss 3927 df-nul 4281 df-if 4485 df-pw 4560 df-sn 4585 df-pr 4587 df-op 4591 df-uni 4864 df-iun 4954 df-br 5104 df-opab 5166 df-mpt 5187 df-tr 5221 df-id 5529 df-eprel 5535 df-po 5543 df-so 5544 df-fr 5586 df-we 5588 df-xp 5637 df-rel 5638 df-cnv 5639 df-co 5640 df-dm 5641 df-rn 5642 df-res 5643 df-ima 5644 df-pred 6251 df-ord 6318 df-on 6319 df-lim 6320 df-suc 6321 df-iota 6445 df-fun 6495 df-fn 6496 df-f 6497 df-f1 6498 df-fo 6499 df-f1o 6500 df-fv 6501 df-riota 7307 df-ov 7354 df-oprab 7355 df-mpo 7356 df-om 7795 df-2nd 7914 df-frecs 8204 df-wrecs 8235 df-recs 8309 df-rdg 8348 df-er 8606 df-en 8842 df-dom 8843 df-sdom 8844 df-sup 9336 df-pnf 11149 df-mnf 11150 df-xr 11151 df-ltxr 11152 df-le 11153 df-sub 11345 df-neg 11346 df-div 11771 df-nn 12112 df-2 12174 df-3 12175 df-n0 12372 df-z 12458 df-uz 12722 df-rp 12870 df-seq 13861 df-exp 13922 df-cj 14938 df-re 14939 df-im 14940 df-sqrt 15074 df-abs 15075 |
This theorem is referenced by: (None) |
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