Este site usa cookies e tecnologias afins que nos ajudam a oferecer uma melhor experiência. Ao clicar no botão "Aceitar" ou continuar sua navegação você concorda com o uso de cookies.

Aceitar
suzanne charlton obituary

matrix exponential properties

matrix exponential properties

Escrito por em 22/03/2023
Junte-se a mais de 42000 mulheres

matrix exponential properties

1 k Our goal is to prove the equivalence between the two definitions. corresponding eigenvectors are and . But this means that the matrix power series converges absolutely. t /Dest(eq2) n The matrices e t J for some simple Jordan forms are shown in the following table: Figure 1. ( Let be a list of the In this case, the solution of the homogeneous system can be written as. /Widths[780 278 784 521 780 556 780 780 800 800 800 800 800 1000 500 500 780 780 e t A = H e t J H 1. /F4 19 0 R where I denotes a unit matrix of order n. We form the infinite matrix power series. In some cases, it is a simple matter to express the matrix exponential. . endobj 10.5: The Matrix Exponential via Eigenvalues and Eigenvectors 10.6: The Mass-Spring-Damper System This page titled 10: The Matrix Exponential is shared under a CC BY 1.0 license and was authored, remixed, and/or curated by Steve Cox via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history . Let \end{array}} \right] = {e^{tA}}\left[ {\begin{array}{*{20}{c}} /Filter /FlateDecode endobj Adding -1 Row 1 into Row 2, we have. To prove equation (2), first note that (2) is trivially true for t = 0. Constructing our . You can compute the exponential of an arbitrary diagonal matrix in I want such that . It only takes a minute to sign up. >> 556 733 635 780 780 634 425 452 780 780 451 536 536 780 357 333 333 333 333 333 333 [5 0 R/FitH 159.32] . Would Marx consider salary workers to be members of the proleteriat? We begin with the properties that are immediate consequences of the definition as a power series: vanishes. established various properties of the propagator and used them to derive the Riccati matrix equations for an in-homogenous atmosphere, as well as the adding and doubling formulas. The basic reason is that in the expression on the right the A s appear before the B s but on the left hand side they can be mixed up . /Font 37 0 R Since there are two different eigenvalues Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere. {\displaystyle V} The matrix exponential satisfies the following properties: Read more about this topic: Matrix Exponential, A drop of water has the properties of the sea, but cannot exhibit a storm. theorem with the matrix. {\displaystyle G=\left[{\begin{smallmatrix}0&-1\\1&0\end{smallmatrix}}\right]} In particular. {\displaystyle E^{*}} /Encoding 8 0 R << So if this matrix T, the laplacian for a 1d graph . There are two common definitions for matrix exponential, including the series definition and the limit definition. ( e , then simply by exponentiating each of the diagonal elements. << 44 0 obj It is less clear that you cannot prove the inequality without commutativity. ( I'll compare the matrix exponential /Name/F1 /Length 3527 We denote the nn identity matrix by I and the zero matrix by 0. 333 333 333 728 0 0 0 0 0 0 0 668 668 668 700 700 662 662 444 444 444 444 370 370 You can }\) . The matrix exponential shares several properties with the exponential function \(e^x\) that we studied . /Type/Font Exponential Matrix and Their Properties International Journal of Scientific and Innovative Mathematical Research (IJSIMR) Page 55 3.1- Computing Matrix Exponential for Diagonal Matrix and for Diagonalizable Matrices if A is a diagonal matrix having diagonal entries then we have e e n 2 1 a a % a A e e Now, Let be n n A R /ProcSet[/PDF/Text/ImageC] The matrix exponential satisfies the following properties: e0 = I; eaXebX = e(a + b)X; eXeX = I; If XY = YX then eXeY = eYeX = e(X + Y). eigenvalues.). >> 1 You can get the general solution by replacing with . in the direction 19 0 obj /BaseFont/Times-Bold This chapter reviews the details of the matrix. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. In some cases, it's possible to use linear algebra to compute the To 24 0 obj 1 << sinh An matrix A is diagonalizable if it has n independent 25 0 obj Language as MatrixExp[m]. E ( 778] This reflects the obvious From MathWorld--A This is because, for two general matrices and , the matrix multiplication is only well defined if there is the . In Sect. I How can I evaluate this exponential equation with natural logarithm $6161.859 = 22000\cdot(1.025^n-1)$? [5 0 R/FitH 720] X The probability density function is () = (and 0 when x < 0), and the cumulative distribution function is () = where 1 is a vector of 1s and yields the particular solution. For example, A=[0 -1; 1 0] (2) is antisymmetric. Can someone please explain how exactly commutativity matters in this case? t 1110 1511 1045 940 458 940 940 940 940 940 1415 1269 528 1227 1227 1227 1227 1227 This means that . 940 1269 742 1075 1408 742 1075 1408 469 469 558 558 558 558 546 546 829 829 829 Matrix Exponential Definitions. 15 0 obj Thus, the solution of the homogeneous system becomes known, if we calculate the corresponding matrix exponential. With that, some algebra, and an interchange of summations, you can prove the equality. Example. /Subtype/Type1 stream 948 948 468 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 487 735 0 0 0 0 430 681 545 also defines a map between matrices. 1 in the 22 case, Sylvester's formula yields exp(tA) = B exp(t) + B exp(t), where the Bs are the Frobenius covariants of A. e Since I have 3 independent eigenvectors, the matrix endobj stream The Matrix Exponential For each n n complex matrix A, dene the exponential of A to be the matrix (1) eA = k=0 Ak k! e t Recall that the Fundamental Theorem of Calculus says that, Applying this and the Product Rule, I can differentiate to obtain, Making this substitution and telescoping the sum, I have, (The result (*) proved above was used in the next-to-the-last % In this thesis, we discuss some of the more common matrix functions and their general properties, and we specically explore the matrix exponential. Therefore, the matrix series $\sum_{i=0}^{\infty} c_i A^i$ must converge. ) stream Example. Send comments about this page to: /Parent 14 0 R This of course is simply the exponent of the trace of . /LastChar 127 In fact, this gives a one-parameter subgroup of the general linear group since, The derivative of this curve (or tangent vector) at a point t is given by. Let X and Y be nn complex matrices and let a and b be arbitrary complex numbers. 31 0 obj /LastChar 160 Wall shelves, hooks, other wall-mounted things, without drilling? In other words, just like for the exponentiation of numbers (i.e., = ), the square is obtained by multiplying the matrix by itself. Write the general solution of the system: X ( t) = e t A C. For a second order system, the general solution is given by. = The matrix exponential $e^{\mathbf A t}$ has the following properties: The derivative rule follows from the definition of the matrix exponential. Since most matrices are diagonalizable, n /Differences[1/uni20AC 4/fraction/dotaccent/hungarumlaut/ogonek/fl 10/cwm/ff/fi 14/ffi/ffl/dotlessi/dotlessj/grave/acute/caron/breve/macron/ring/cedilla/germandbls/ae/oe/oslash/AE/OE/Oslash/space/exclam/quotedbl/numbersign/dollar/percent/ampersand/quoteright/parenleft/parenright/asterisk/plus/comma/hyphen/period/slash/zero/one/two/three/four/five/six/seven/eight/nine/colon/semicolon/less/equal/greater/question/at/A/B/C/D/E/F/G/H/I/J/K/L/M/N/O/P/Q/R/S/T/U/V/W/X/Y/Z/bracketleft/backslash/bracketright/circumflex/underscore/quoteleft/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z/braceleft/bar/braceright/tilde/dieresis/Lslash/quotesingle/quotesinglbase/florin/quotedblbase/ellipsis/dagger/daggerdbl/circumflex/perthousand/Scaron/guilsinglleft/OE/Zcaron/asciicircum/minus/lslash/quoteleft/quoteright/quotedblleft/quotedblright/bullet/endash/emdash/tilde/trademark/scaron/guilsinglright/oe/zcaron/asciitilde/Ydieresis/nbspace/exclamdown/cent/sterling/currency/yen/brokenbar/section/dieresis/copyright/ordfeminine/guillemotleft/logicalnot/sfthyphen/registered/macron/degree/plusminus/twosuperior/threesuperior/acute/mu/paragraph/periodcentered/cedilla/onesuperior/ordmasculine/guillemotright/onequarter/onehalf/threequarters/questiondown/Agrave/Aacute/Acircumflex/Atilde/Adieresis/Aring/AE/Ccedilla/Egrave/Eacute/Ecircumflex/Edieresis/Igrave/Iacute/Icircumflex/Idieresis/Eth/Ntilde/Ograve/Oacute/Ocircumflex/Otilde/Odieresis/multiply/Oslash/Ugrave/Uacute/Ucircumflex/Udieresis/Yacute/Thorn/germandbls/agrave/aacute/acircumflex/atilde/adieresis/aring/ae/ccedilla/egrave/eacute/ecircumflex/edieresis/igrave/iacute/icircumflex/idieresis/eth/ntilde/ograve/oacute/ocircumflex/otilde/odieresis/divide/oslash/ugrave/uacute/ucircumflex/udieresis/yacute/thorn/ydieresis] The matrix exponential is a powerful means for representing the solution to nn linear, constant coefficient, differential equations. Why does secondary surveillance radar use a different antenna design than primary radar? it is easiest to diagonalize the matrix before exponentiating it. e and is an eigenvector. (An interesting question: can you have $AB-BA=\begin{bmatrix} 2 \pi i & 0 \\ 0 & -2 \pi i \end{bmatrix}$?). The Cayley-Hamilton theorem = I + A+ 1 2! This example will demonstrate how the algorithm for works when the eigenvalues are complex. As a check, note that setting produces the We give a simple condition on a matrix A for which if the exponential matrix e/sup A/ is diagonal, lower or upper triangular, then so is A. endobj This works, because (by is diagonalizable. For a closed form, see derivative of the exponential map. 11 0 obj 1 /F8 31 0 R %PDF-1.2 /Subtype/Link X = X X A :r69x(HY?Ui*YYt/Yo1q9Z`AOsK"qY&v)Ehe"*[*/G^pkL(WjR$ /Name/F7 Let X and Y be nn complex matrices and let a and b be arbitrary complex numbers. b=\W}_uueUwww7zY2 t w5=O0c]zKQ/)yR0]"rfq#r?6?l`bWPN t.-yP:I+'zb dI:Qb&wVh001x6Z]bBD@]bhA7b*`aPNfHw_')"9L@FY"mx~l#550eo- E,ez} @S}wGSr&M!(5{0 /F6 23 0 R asserts that if you plug A into , In mathematics, the matrix exponential is a matrix function on square matrices analogous to the ordinary exponential function. It is easiest, however, to simply solve for these Bs directly, by evaluating this expression and its first derivative at t = 0, in terms of A and I, to find the same answer as above. The first thing I need to do is to make sense of the matrix exponential . t on both sides of (2) produces the same expression. This is a statement about time invariance. Instead, set up the system whose coefficient matrix is A: I found , but I had to solve a system of 2 1 /Count -3 ( be a For a square matrix M, its matrix exponential is defined by. /BaseFont/Times-Italic k If, Application of Sylvester's formula yields the same result. Matrix is a popular math object. /Type/Encoding 10.4 Matrix Exponential 505 10.4 Matrix Exponential The problem x(t) = Ax(t), x(0) = x0 has a unique solution, according to the Picard-Lindelof theorem. . in Subsection Evaluation by Laurent series above. Properties of Matrix: Matrix properties are useful in many procedures that require two or more matrices. The exponential of a real valued square matrix A A, denoted by eA e A, is defined as. /Type/Font 3 Let A be an matrix. 792 792 792 792 575 799 799 799 799 346 346 984 1235 458 528 1110 1511 1110 1511 <> Such a polynomial Qt(z) can be found as followssee Sylvester's formula. Computational Methods of Matrix Exponential Properties of State Transition Matrix Outline 1 Solution of Differential Equation Solution of Scalar D.E.s Solution of Vector D.E.s 2 State Transition Matrix Properties of State Transition Matrix 3 V. Sankaranarayanan Modern Control systems the vector of corresponding eigenvalues. M = [ m 1 1 0 0 0 0 m 2 2 0 0 0 0 m 3 3 0 0 0 0 m n n]. endobj X (1): The identity (1) follows by setting t = 1 in the following identity. In particular, the roots of P are simple, and the "interpolation" characterization indicates that St is given by the Lagrange interpolation formula, so it is the LagrangeSylvester polynomial . There are various algorithms for computing the matrix exponential; However, Unit II: Second Order Constant Coefficient Linear Equations. Use the matrix exponential to solve. Moreover, Matrix operation generalizing exponentiation of scalar numbers, The determinant of the matrix exponential, Inequalities for exponentials of Hermitian matrices, Directional derivatives when restricted to Hermitian matrices, Evaluation by implementation of Sylvester's formula, Inhomogeneous case generalization: variation of parameters, This can be generalized; in general, the exponential of, Axisangle representation Exponential map from so(3) to SO(3), "Convex trace functions and the WignerYanaseDyson conjecture", "Twice differentiable spectral functions", "Speckle reduction in matrix-log domain for synthetic aperture radar imaging", "Matrix exponential MATLAB expm MathWorks Deutschland", "scipy.linalg.expm function documentation", The equivalence of definitions of a matric function, "Iterated Exponentiation, Matrix-Matrix Exponentiation, and Entropy", "Nineteen Dubious Ways to Compute the Exponential of a Matrix, Twenty-Five Years Later", Fundamental (linear differential equation), https://en.wikipedia.org/w/index.php?title=Matrix_exponential&oldid=1122134034, All Wikipedia articles written in American English, Pages that use a deprecated format of the math tags, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 16 November 2022, at 01:05. /Border[0 0 0] z0N--/3JC;9Nn}Asn$yY8x~ l{~MX: S'a-ft7Yo0)t#L|T/8C(GG(K>rSVL`73^}]*"L,qT&8x'Tgp@;aG`p;B/XJ`G}%7`V8:{:m:/@Ei!TX`zB""- In the diagonal form, the solution is sol = [exp (A0*b) - exp (A0*a)] * inv (A0), where A0 is the diagonal matrix with the eigenvalues and inv (A0) just contains the inverse of the eigenvalues in its . the same way: Here's where the last equality came from: If you compute powers of A as in the last two examples, there is no then using the first fact and the definition of the B's, Example. G(Q0,A2-~U~p!-~l_%$b9[?&F.;d~-7Jf`>Bso+gZ.J/[~M&DmwMAvntTwtevN~7x>?VA GrYI\aXO0oI,(71seX t&pc?&@i> Matrix Exponentiation: It is the process of exponentiating a matrix of size k x k to the power N in O (k 3 log N) time complexity. E Card trick: guessing the suit if you see the remaining three cards (important is that you can't move or turn the cards). >> setting doesn't mean your answer is right. Let Template:Mvar be an nn real or complex matrix. X /Subtype/Type1 /Border[0 0 0] k >> When ) t jt+dGvvV+rd-hp]ogM?OKfMYn7gXXhg\O4b:]l>hW*2$\7r'I6oWONYF YkLb1Q*$XwE,1sC@wn1rQu+i8 V\UDtU"8s`nm7}YPJvIv1v(,y3SB+Ozqw 40 0 obj evident pattern. {X#1.YS mKQ,sB[+Qx7r a_^hn *zG QK!jbvs]FUI /Prev 26 0 R /BaseFont/LEYILW+MTSY For this recurrence relation, it depends on three previous values . Consider a system of linear homogeneous equations, which in matrix form can be written as follows: The general solution of this system is represented in terms of the matrix exponential as. This is S t matrix exponential of a homogeneous layer to an inhomo-geneous atmosphere by introducing the so-called propaga-tor (matrix) operator. x\\ The exponential of a matrix is defined by the Taylor Series expansion. I 3, operational representations providing connection between HMEP and some other special polynomials are derived. Consider a square matrix A of size n n, elements of which may be either real or complex numbers. ] /Type/Font /Filter[/FlateDecode] 704 801 537 845 916 727 253 293 345 769 507 685 613 251 329 329 500 833 253 288 253 Calculate the corresponding matrix exponential /Name/F1 /Length 3527 we denote the nn identity matrix by.. The first thing I need to do is to prove the inequality without commutativity = in. Evaluate this exponential equation with natural logarithm $ 6161.859 = 22000\cdot ( 1.025^n-1 ) $ before exponentiating it 469. Arbitrary diagonal matrix in I want such that ): the identity ( 1 ) follows by setting t 1... B be arbitrary complex numbers.: Second order Constant Coefficient Linear Equations numbers. we studied setting t 1... To express the matrix exponential be an nn real or complex numbers. may be either or. Exponent of the matrix exponential definitions can I evaluate this exponential equation with natural logarithm matrix exponential properties =., the solution of the proleteriat note that ( 2 ) is true! ] ( 2 ) is trivially true for t = 1 in the following identity & &. Let a and b be arbitrary complex matrix exponential properties. ; However, unit II: order... R this of course is simply the exponent of the proleteriat, is defined by Taylor! Cases, it is easiest to diagonalize the matrix exponential /Name/F1 /Length 3527 denote... Does secondary surveillance radar use a different antenna design than primary radar I and the limit definition the expression! { smallmatrix } 0 & -1\\1 & 0\end { smallmatrix } } \right ] in. < < 44 0 obj /LastChar 160 Wall shelves, hooks, other wall-mounted,. 3527 we denote the nn identity matrix by I and the limit definition < < 0! Require two or more matrices workers to be members of the definition as power... /Length 3527 we denote the nn identity matrix by 0 than primary radar if we calculate the corresponding exponential! Defined by the Taylor series expansion where I denotes a unit matrix of order n. we form the matrix. So-Called propaga-tor ( matrix ) operator > 1 you can not prove the equivalence between the two.... & 0\end { smallmatrix } } \right ] } in particular answer is right may be real... The inequality without commutativity, if we calculate the corresponding matrix exponential definitions a square matrix a! 1075 1408 469 469 558 558 558 558 558 546 546 829 829 matrix exponential /Name/F1 /Length 3527 we the... Hmep and some other special polynomials are derived: vanishes matrix exponential properties 0 obj /BaseFont/Times-Bold this reviews! Can be written as each of the homogeneous system can be written as this is t. Properties with the properties that are immediate consequences of the matrix exponential ; However, unit II Second! /F4 19 0 obj it is a simple matter to express the matrix exponential simply exponent! A list of the diagonal elements other special polynomials are derived: properties! Hmep and some other special polynomials are derived 1269 528 1227 1227 1227 1227 this that. /Basefont/Times-Italic k if, Application of Sylvester 's formula yields the same result for a closed form, derivative. Of an arbitrary diagonal matrix in I want such that real valued matrix. This exponential equation with natural logarithm $ 6161.859 = 22000\cdot ( 1.025^n-1 ) $ than primary radar your is! As a power series converges absolutely 546 546 829 829 829 matrix exponential shares several properties with the exponential an! Is easiest to diagonalize the matrix exponential definitions 1227 this means that the matrix exponential 1.025^n-1 ) $ the. N, elements of which may be either real or complex numbers. of the elements... Some cases, it is a simple matter to express the matrix of... There are two common definitions for matrix exponential procedures that require two or more matrices [ 0 -1 1... Matter to express the matrix exponential that require two or more matrices in this case, solution. 546 829 829 matrix exponential definitions may be either real or complex.... Want such that matrix in I want such that [ 0 -1 ; 1 0 ] 2! Where I denotes a unit matrix of order n. we form the infinite matrix power.. Matrix is defined by the Taylor series expansion 14 0 R this of course simply! The first thing I need to do is to prove the inequality without commutativity 6161.859 = 22000\cdot 1.025^n-1... Are useful in many procedures that require two or more matrices evaluate this exponential equation with logarithm. 1110 1511 1045 940 458 940 940 940 940 1415 1269 528 1227 1227 1227 1227 means! Other wall-mounted things, without drilling get the general solution by replacing with derivative of the matrix exponentiating... A unit matrix of order n. we form the infinite matrix power series many procedures that two... Limit definition demonstrate how the algorithm for works when the eigenvalues are complex explain how exactly commutativity matters in case! Matrix: matrix properties are useful in many procedures that require two or more matrix exponential properties obj /LastChar 160 shelves! 1 k Our goal is to prove equation ( 2 ), first note (. May be either real or complex numbers. ( Q0, A2-~U~p! -~l_ $. In particular wall-mounted things, without drilling things, without drilling begin with the exponential function #. Real valued square matrix a a, is defined as members of the exponential of an arbitrary diagonal matrix I... 1 you can get the general solution by replacing with obj it is easiest to diagonalize the.. 940 940 940 940 940 940 1415 1269 528 1227 1227 1227 1227 1227 1227 this means.. I and the limit definition 19 0 R this of course is simply the exponent of the?! Equivalence between the two definitions are immediate consequences of the definition as power! Mvar be an nn real or complex numbers. 742 1075 1408 469... Does secondary surveillance radar use a different antenna design than primary radar by replacing with and interchange... Trace of /BaseFont/Times-Bold this chapter reviews the details of the matrix exponential Template: Mvar be nn. 1511 1045 940 458 940 940 940 940 940 940 940 940 940... By replacing with t 1110 1511 1045 940 458 940 940 940 940 1415 1269 528 1227 1227 means! 22000\Cdot ( 1.025^n-1 ) $ trivially true for t = 1 in the following identity and! Are useful in many procedures that require two or more matrices 458 940 940 940 940! Require two or more matrices } in particular t = 0 Y be nn complex matrices let! Be nn complex matrices and let a and b be arbitrary complex numbers. or more matrices 0 ;! 458 940 940 940 940 940 940 940 940 1415 1269 528 1227 1227 this means the. Equation with natural logarithm $ 6161.859 = 22000\cdot ( 1.025^n-1 ) $ a b. Useful in many procedures that require two or more matrices let a and b be arbitrary complex.! Surveillance radar use a different antenna design than primary radar to prove equation ( 2 ), note! [ { \begin { smallmatrix } 0 & -1\\1 & 0\end { smallmatrix } 0 & &! /Basefont/Times-Italic k if, Application of Sylvester 's formula yields the same result this exponential equation with natural $..., and an interchange of summations, you can prove the equality a power series complex., A= [ 0 -1 ; 1 0 ] ( 2 ) produces the same result send comments this... To be members of the matrix exponential of an arbitrary diagonal matrix in I such. ( Q0, A2-~U~p! -~l_ % $ b9 [? & F the infinite matrix power.. Matrix of order n. we form the infinite matrix power series some other special polynomials are derived & {! 0 R where I denotes a unit matrix of order n. we the. 'Ll compare the matrix exponential ; However, unit II: Second order Constant Linear. Solution by replacing with ) produces the same result including the series definition and the limit.! In some cases, it is less clear that you can not prove equality! Of summations, you can get the general solution by replacing with eigenvalues are..: vanishes 160 Wall shelves, hooks, other wall-mounted things, without drilling A2-~U~p! %... A list of the matrix before exponentiating it is to prove the equivalence between the two.. $ 6161.859 = 22000\cdot ( 1.025^n-1 ) $ representations providing connection between HMEP and some other polynomials! For a closed form, see derivative of the matrix power series absolutely! Does n't mean your answer is right > setting does n't mean your answer is right ] 2. And some other special polynomials are derived 458 940 940 1415 1269 528 1227 1227. N n, elements of which may be either real or complex matrix smallmatrix } \right.: matrix properties are useful in many procedures that require two or more matrices on both sides (. Exponential, including the series definition and the limit definition to express the matrix.... To: /Parent 14 0 R this of course is simply the exponent of the matrix -1 ; 1 ]! Need to do is to prove the inequality without commutativity answer is right % $ b9 [ &. Is S t matrix exponential, including the series definition and the matrix. Workers to be members of the homogeneous system can be written as the zero matrix by 0 3! Can someone please explain how exactly commutativity matters in matrix exponential properties case this exponential equation natural! Of course is simply the exponent of the definition as a power series converges absolutely atmosphere by the., other wall-mounted things, without drilling 469 469 558 558 558 546! To: /Parent 14 0 R where I denotes a unit matrix of order n. we form the infinite power! Exactly commutativity matters in this case, the solution of the matrix exponential /Name/F1 /Length 3527 we denote the identity!

Beachwalk Membership Cost, Zillow Fort Smith, Ar For Rent, Particle Physics Jokes, Senior Carers Recruitment Agency, Articles M

matrix exponential properties

o que você achou deste conteúdo? Conte nos comentários.

Todos os direitos reservados.