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improvements in pages 5 and 7 of the tutorial.

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Benoit Jacob
2010-10-18 09:09:30 -04:00
parent 1c15a6d96f
commit 3404d5fb14
4 changed files with 46 additions and 35 deletions
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23
doc/C05_TutorialAdvancedInitialization.dox
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@@ -67,8 +67,8 @@ Example: \include Tutorial_AdvancedInitialization_Zero.cpp
Output: \verbinclude Tutorial_AdvancedInitialization_Zero.out
</td></tr></table>
Similarly, the static method \link DenseBase::Constant() Constant\endlink(value) sets all coefficients to \c
value. If the size of the object needs to be specified, the additional arguments go before the \c value
Similarly, the static method \link DenseBase::Constant() Constant\endlink(value) sets all coefficients to \c value.
If the size of the object needs to be specified, the additional arguments go before the \c value
argument, as in <tt>MatrixXd::Constant(rows, cols, value)</tt>. The method \link DenseBase::Random() Random()
\endlink fills the matrix or array with random coefficients. The identity matrix can be obtained by calling
\link MatrixBase::Identity() Identity()\endlink; this method is only available for Matrix, not for Array,
@@ -102,13 +102,15 @@ Output: \verbinclude Tutorial_AdvancedInitialization_ThreeWays.out
A summary of all pre-defined matrix, vector and array objects can be found in the \ref QuickRefPage.
\section TutorialAdvancedInitializationTemporaryObjects Temporary matrices and arrays
\section TutorialAdvancedInitializationTemporaryObjects Usage as temporary objects
As shown above, static methods as Zero() and Constant() can be used to initialize to variables at the time of
As shown above, static methods as Zero() and Constant() can be used to initialize variables at the time of
declaration or at the right-hand side of an assignment operator. You can think of these methods as returning a
matrix or array (in fact, they return a so-called \ref TopicEigenExpressionTemplates "expression object" which
evaluates to a matrix when needed). This matrix can also be used as a temporary object. The second example in
the \ref GettingStarted guide, which we reproduced here, already illustrates this.
matrix or array; in fact, they return so-called \ref TopicEigenExpressionTemplates "expression objects" which
evaluate to a matrix or array when needed, so that this syntax does not incur any overhead.
These expressions can also be used as a temporary object. The second example in
the \ref GettingStarted guide, which we reproduce here, already illustrates this.
<table class="tutorial_code"><tr><td>
Example: \include QuickStart_example2_dynamic.cpp
@@ -117,9 +119,10 @@ Example: \include QuickStart_example2_dynamic.cpp
Output: \verbinclude QuickStart_example2_dynamic.out
</td></tr></table>
The expression <tt>m + MatrixXf::Constant(3,3,1.2)</tt> constructs the 3-by-3 matrix with all its coefficients
equal to 1.2 and adds it to \c m ; in other words, it adds 1.2 to all the coefficients of \c m . The
comma-initializer can also be used to construct temporary objects. The following example constructs a random
The expression <tt>m + MatrixXf::Constant(3,3,1.2)</tt> constructs the 3-by-3 matrix expression with all its coefficients
equal to 1.2 plus the corresponding coefficient of \a m.
The comma-initializer, too, can also be used to construct temporary objects. The following example constructs a random
matrix of size 2-by-3, and then multiplies this matrix on the left with
\f$ \bigl[ \begin{smallmatrix} 0 & 1 \\ 1 & 0 \end{smallmatrix} \bigr] \f$.