Series on Blogging with LaTeX This is the 3rd post in the series. Previous ones: Many of the examples shown here were adapted from the Wikipedia article Displaying a formula, which is actually about formulas in Math Markup. Multiline EquationsYou can present equations with several lines, using the array statement. Inside its declaration you must :
Example: {lcr} means: 3 columns with indentations respectively left, center and right \begin{array}{lcl} z & = & a \\ f(x,y,z) & = & x + y + z \end{array} \begin{array}{rcr} z & = & a \\ f(x,y,z) & = & x + y + z \end{array} \begin{array}{rcl} f: R^3 & \to & R \\ (x,y,z) & \to & x + y + z \\ f(x,y,z) & = & x + y + z \end{array} \begin{array} {lcl} f(x) & = & (a+b)^2 \\ & = & a^2+2ab+b^2 \end{array} . Case definitionsUsed when a definition have two or more cases. Use the case statement. Notice that the spaces after the instances of if were included inside the mbox declarations. f(n) = \begin{cases} n/2, & \mbox{if } n\mbox{ is even} \\ 3n+1, & \mbox{if } n\mbox{ is odd} \end{cases} . Simultaneous EquationsHere we have a very simple application of the case statement. \begin{cases} 3x + 5y + z \\ 7x – 2y + 4z \\ -6x + 3y + 2z \end{cases} . MatricesMatrices can be assembled by using the array statement, like in this example: \left| \begin{array}{cc} x_{11} & x_{12} \\ x_{21} & x_{22} \end{array} \right| Matrix frames are provided by \left and \right. If you suppress these statements, it will be displayed like: \begin{array}{cc} A & B \\ C & D \end{array} However, there is another statement, the matrix declaration, slightly easier to use: \begin{matrix} x & y \\ z & v \end{matrix} The frames of the matrix can be displayed in several forms, by just changing the matrix declaration to vmatrix, Vmatrix, bmatrix, Bmatrix or pmatrix, as shown ahead: \begin{vmatrix} x & y \\ z & v \end{vmatrix} \begin{Vmatrix} x & y \\ z & v \end{Vmatrix} \begin{bmatrix} x & y \\ z & v \end{bmatrix} \begin{Bmatrix} x & y \\ z & v \end{Bmatrix} \begin{pmatrix} x & y \\ z & v \end{pmatrix} As a final example, let us construct more complicated matrices and matricial expressions: \begin{bmatrix} 0 & \cdots & 0 \\ \vdots & \ddots & \vdots \\ 0 & \cdots & 0 \end{bmatrix} Now, we will show a first matricial expression: \left[ \begin{array}{c} x_1 \\ x_2 \end{array} \right] = \begin{bmatrix} A & B \\ C & D \end{bmatrix} \times \left[ \begin{array}{c} y_1 \\ y_2 \end{array} \right] and, here is another example, now using two kinds of vectors: \begin{bmatrix} xz & xw \\ yz & yw \end{bmatrix} = \left[ \begin{array}{c} x \\ y \end{array} \right] \times \left[ \begin{array}{cc} z & w \end{array} \right]
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