MATLAB Programming Fundamentals

56Infinity and NaN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Infinity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .NaN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Infinity and NaN Functions . . . . . . . . . . . . . . . . . . . .4-184-184-184-20Identifying Numeric Classes . . . . . . . . . . . . . . . . . . . . .4-21Display Format for Numeric Values . . . . . . . . . . . . . . .Default Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Display Format Examples . . . . . . . . . . . . . . . . . . . . . .Setting Numeric Format in a Program . . . . . . . . . . . .4-224-224-224-23Function Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-25The Logical ClassFind Array Elements That Meet a Condition . . . . . . . . .Apply a Single Condition . . . . . . . . . . . . . . . . . . . . . . .Apply Multiple Conditions . . . . . . . . . . . . . . . . . . . . . .Replace Values that Meet a Condition . . . . . . . . . . . . . .5-25-25-45-5Determine if Arrays Are Logical . . . . . . . . . . . . . . . . . . .Identify Logical Matrix . . . . . . . . . . . . . . . . . . . . . . . . .Test an Entire Array . . . . . . . . . . . . . . . . . . . . . . . . . . .Test Each Array Element . . . . . . . . . . . . . . . . . . . . . . .Summary Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-75-75-75-85-9Reduce Logical Arrays to Single Value . . . . . . . . . . . . .5-10Truth Table for Logical Operations . . . . . . . . . . . . . . .5-13Characters and StringsCreating Character Arrays . . . . . . . . . . . . . . . . . . . . . . . .Creating a Character String . . . . . . . . . . . . . . . . . . . . .6-26-2ix

xContentsCreating a Rectangular Character Array . . . . . . . . . . . .Identifying Characters in a String . . . . . . . . . . . . . . . .Working with Space Characters . . . . . . . . . . . . . . . . . .Expanding Character Arrays . . . . . . . . . . . . . . . . . . . . .6-36-46-56-6Cell Arrays of Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . .Converting to a Cell Array of Strings . . . . . . . . . . . . . .Functions for Cell Arrays of Strings . . . . . . . . . . . . . . .6-76-76-8Formatting Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Functions that Use Format Strings . . . . . . . . . . . . . . .The Format String . . . . . . . . . . . . . . . . . . . . . . . . . . .Input Value Arguments . . . . . . . . . . . . . . . . . . . . . . . .The Formatting Operator . . . . . . . . . . . . . . . . . . . . . .Constructing the Formatting Operator . . . . . . . . . . . .Setting Field Width and Precision . . . . . . . . . . . . . . . .Restrictions for Using Identifiers . . . . . . . . . . . . . . . .6-106-106-116-126-136-146-196-21String Comparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Comparing Strings for Equality . . . . . . . . . . . . . . . . .Comparing for Equality Using Operators . . . . . . . . . .Categorizing Characters Within a String . . . . . . . . . . .6-236-236-246-24Searching and Replacing . . . . . . . . . . . . . . . . . . . . . . . .6-26Converting from Numeric to String . . . . . . . . . . . . . . .Function Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .Converting to a Character Equivalent . . . . . . . . . . . . .Converting to a String of Numbers . . . . . . . . . . . . . . .Converting to a Specific Radix . . . . . . . . . . . . . . . . . .6-286-286-296-296-29Converting from String to Numeric . . . . . . . . . . . . . . .Function Summary . . . . . . . . . . . . . . . . . . . . . . . . . . .Converting from a Character Equivalent . . . . . . . . . . .Converting from a Numeric String . . . . . . . . . . . . . . .Converting from a Specific Radix . . . . . . . . . . . . . . . .6-306-306-306-316-31Function Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-33

7Dates and TimeRepresent Dates and Times in MATLAB . . . . . . . . . . . .7-2Specify Time Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-6Set Date and Time Display Format . . . . . . . . . . . . . . . . .Formats for Individual Date and Duration Arrays . . . . .datetime Display Format . . . . . . . . . . . . . . . . . . . . . .duration Display Format . . . . . . . . . . . . . . . . . . . . . .calendarDuration Display Format . . . . . . . . . . . . .Default datetime Format . . . . . . . . . . . . . . . . . . . . .7-87-87-87-97-107-11Generate Sequence of Dates and Time . . . . . . . . . . . . .Sequence of Datetime or Duration Values BetweenEndpoints with Step Size . . . . . . . . . . . . . . . . . . . .Add Duration or Calendar Duration to Create Sequence ofDates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Specify Length and Endpoints of Date or DurationSequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Sequence of Datetime Values Using Calendar Rules . .7-137-177-18Share Code and Data Across Locales . . . . . . . . . . . . . .Write Locale-Independent Date and Time Code . . . . . .Write Dates in Other Languages . . . . . . . . . . . . . . . . .Read Dates in Other Languages . . . . . . . . . . . . . . . . .7-227-227-237-24Extract or Assign Date and Time Components ofDatetime Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-25Combine Date and Time from Separate Variables . . . .7-30Date and Time Arithmetic . . . . . . . . . . . . . . . . . . . . . . .7-32Compare Dates and Time . . . . . . . . . . . . . . . . . . . . . . . .7-40Plot Dates and Durations . . . . . . . . . . . . . . . . . . . . . . . .7-44Core Functions Supporting Date and Time Arrays . . .7-557-137-16xi

8xiiContentsConvert Between Datetime Arrays, Numbers, andStrings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Convert Between Datetime and Strings . . . . . . . . . . .Convert Between Datetime and Date Vectors . . . . . . .Convert Serial Date Numbers to Datetime . . . . . . . . .Convert Datetime Arrays to Numeric Values . . . . . . . .7-567-567-577-587-597-59Carryover in Date Vectors and Strings . . . . . . . . . . . . .7-61Converting Date Vector Returns Unexpected Output .7-62Categorical ArraysCreate Categorical Arrays . . . . . . . . . . . . . . . . . . . . . . . .8-2Convert Table Variables Containing Strings toCategorical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-6Plot Categorical Data . . . . . . . . . . . . . . . . . . . . . . . . . . .8-11Compare Categorical Array Elements . . . . . . . . . . . . . .8-19Combine Categorical Arrays . . . . . . . . . . . . . . . . . . . . .8-22Combine Categorical Arrays Using Multiplication . . .8-26Access Data Using Categorical Arrays . . . . . . . . . . . . .Select Data By Category . . . . . . . . . . . . . . . . . . . . . . .Common Ways to Access Data Using CategoricalArrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-298-29Work with Protected Categorical Arrays . . . . . . . . . . .8-37Advantages of Using Categorical Arrays . . . . . . . . . . .Natural Representation of Categorical Data . . . . . . . .Mathematical Ordering for Strings . . . . . . . . . . . . . . .Reduce Memory Requirements . . . . . . . . . . . . . . . . . .8-428-428-428-428-29

Ordinal Categorical Arrays . . . . . . . . . . . . . . . . . . . . . .Order of Categories . . . . . . . . . . . . . . . . . . . . . . . . . . .How to Create Ordinal Categorical Arrays . . . . . . . . .Working with Ordinal Categorical Arrays . . . . . . . . . .8-458-458-458-48Core Functions Supporting Categorical Arrays . . . . . .8-49Tables9Create a Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-2Add and Delete Table Rows . . . . . . . . . . . . . . . . . . . . . . .9-9Add and Delete Table Variables . . . . . . . . . . . . . . . . . .9-13Clean Messy and Missing Data in Tables . . . . . . . . . . .9-17Modify Units, Descriptions and Table Variable Names9-24Access Data in a Table . . . . . . . . . . . . . . . . . . . . . . . . . .Ways to Index into a Table . . . . . . . . . . . . . . . . . . . . .Create Table from Subset of Larger Table . . . . . . . . . .Create Array from the Contents of Table . . . . . . . . . . .9-289-289-299-32Calculations on Tables . . . . . . . . . . . . . . . . . . . . . . . . . .9-36Split Data into Groups and Calculate Statistics . . . . .9-40Split Table Data Variables and Apply Functions . . . . .9-44Advantages of Using Tables . . . . . . . . . . . . . . . . . . . . . .Conveniently Store Mixed-Type Data in SingleContainer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Access Data Using Numeric or Named Indexing . . . . .Use Table Properties to Store Metadata . . . . . . . . . . .9-49Grouping Variables To Split Data . . . . . . . . . . . . . . . . .Grouping Variables . . . . . . . . . . . . . . . . . . . . . . . . . . .Group Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9-569-569-569-499-529-53xiii

The Split-Apply-Combine Workflow . . . . . . . . . . . . . . .Missing Group Values . . . . . . . . . . . . . . . . . . . . . . . . .1011xivContents9-579-58StructuresCreate a Structure Array . . . . . . . . . . . . . . . . . . . . . . . .10-2Access Data in a Structure Array . . . . . . . . . . . . . . . . .10-6Concatenate Structures . . . . . . . . . . . . . . . . . . . . . . . .10-10Generate Field Names from Variables . . . . . . . . . . . .10-12Access Data in Nested Structures . . . . . . . . . . . . . . . .10-13Access Elements of a Nonscalar Struct Array . . . . . .10-15Ways to Organize Data in Structure Arrays . . . . . . . .Plane Organization . . . . . . . . . . . . . . . . . . . . . . . . . .Element-by-Element Organization . . . . . . . . . . . . . . .10-1710-1710-19Memory Requirements for a Structure Array . . . . . .10-21Cell ArraysWhat Is a Cell Array? . . . . . . . . . . . . . . . . . . . . . . . . . . .11-2Create a Cell Array . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11-3Access Data in a Cell Array . . . . . . . . . . . . . . . . . . . . . .11-5Add Cells to a Cell Array . . . . . . . . . . . . . . . . . . . . . . . .11-8Delete Data from a Cell Array . . . . . . . . . . . . . . . . . . . .11-9

1213Combine Cell Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . .11-10Pass Contents of Cell Arrays to Functions . . . . . . . . .11-11Preallocate Memory for a Cell Array . . . . . . . . . . . . .11-16Cell vs. Struct Arrays . . . . . . . . . . . . . . . . . . . . . . . . . .11-17Multilevel Indexing to Access Parts of Cells . . . . . . .11-19Function HandlesCreate Function Handle . . . . . . . . . . . . . . . . . . . . . . . . .What Is a Function Handle? . . . . . . . . . . . . . . . . . . . .Creating Function Handles . . . . . . . . . . . . . . . . . . . . .Anonymous Functions . . . . . . . . . . . . . . . . . . . . . . . . .Arrays of Function Handles . . . . . . . . . . . . . . . . . . . .Saving and Loading Function Handles . . . . . . . . . . . .12-212-212-212-412-412-5Pass Function to Another Function . . . . . . . . . . . . . . .12-6Call Local Functions Using Function Handles . . . . . . .12-8Compare Function Handles . . . . . . . . . . . . . . . . . . . . .Compare Handles Constructed from Named FunctionCompare Handles to Anonymous Functions . . . . . . . .Compare Handles to Nested Functions . . . . . . . . . . .Call Local Functions Using Function Handles . . . . . .12-1012-1012-1012-1112-12Map ContainersOverview of the Map Data Structure . . . . . . . . . . . . . .13-2Description of the Map Class . . . . . . . . . . . . . . . . . . . . .Properties of the Map Class . . . . . . . . . . . . . . . . . . . .13-413-4xv

Methods of the Map Class . . . . . . . . . . . . . . . . . . . . . .14xviContents13-5Creating a Map Object . . . . . . . . . . . . . . . . . . . . . . . . . .Constructing an Empty Map Object . . . . . . . . . . . . . .Constructing An Initialized Map Object . . . . . . . . . . .Combining Map Objects . . . . . . . . . . . . . . . . . . . . . . .13-613-613-713-8Examining the Contents of the Map . . . . . . . . . . . . . . .13-9Reading and Writing Using a Key Index . . . . . . . . . . .Reading From the Map . . . . . . . . . . . . . . . . . . . . . . .Adding Key/Value Pairs . . . . . . . . . . . . . . . . . . . . . .Building a Map with Concatenation . . . . . . . . . . . . .13-1013-1013-1113-12Modifying Keys and Values in the Map . . . . . . . . . . . .Removing Keys and Values from the Map . . . . . . . . .Modifying Values . . . . . . . . . . . . . . . . . . . . . . . . . . . .Modifying Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Modifying a Copy of the Map . . . . . . . . . . . . . . . . . .13-1513-1513-1613-1613-17Mapping to Different Value Types . . . . . . . . . . . . . . . .Mapping to a Structure Array . . . . . . . . . . . . . . . . . .Mapping to a Cell Array . . . . . . . . . . . . . . . . . . . . . .13-1813-1813-19Combining Unlike ClassesValid Combinations of Unlike Classes . . . . . . . . . . . . .14-2Combining Unlike Integer Types . . . . . . . . . . . . . . . . . .Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Example of Combining Unlike Integer Sizes . . . . . . . .Example of Combining Signed with Unsigned . . . . . . .14-314-314-314-4Combining Integer and Noninteger Data . . . . . . . . . . .14-6Combining Cell Arrays with Non-Cell Arrays . . . . . . .14-7Empty Matrices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14-8

Concatenation Examples . . . . . . . . . . . . . . . . . . . . . . . .Combining Single and Double Types . . . . . . . . . . . . . .Combining Integer and Double Types . . . . . . . . . . . . .Combining Character and Double Types . . . . . . . . . .Combining Logical and Double Types . . . . . . . . . . . .1514-914-914-914-1014-10Using ObjectsMATLAB Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Getting Oriented . . . . . . . . . . . . . . . . . . . . . . . . . . . . .What Are Objects and Why Use Them? . . . . . . . . . . . .Working with Objects . . . . . . . . . . . . . . . . . . . . . . . . .Objects In the MATLAB Language . . . . . . . . . . . . . . .Other Kinds of Objects Used by MATLAB . . . . . . . . . .15-215-215-215-315-315-3General Purpose Vs. Specialized Arrays . . . . . . . . . . . .How They Differ . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Using General-Purpose Data Structures . . . . . . . . . . .Using Specialized Objects . . . . . . . . . . . . . . . . . . . . . .15-515-515-515-6Key Object Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . .Basic Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Classes Describe How to Create Objects . . . . . . . . . . .Properties Contain Data . . . . . . . . . . . . . . . . . . . . . . .Methods Implement Operations . . . . . . . . . . . . . . . . .Events are Notices Broadcast to Listening Objects . .15-815-815-815-915-915-10Creating Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Class Constructor . . . . . . . . . . . . . . . . . . . . . . . . . . .When to Use Package Names . . . . . . . . . . . . . . . . . .15-1115-1115-11Accessing Object Data . . . . . . . . . . . . . . . . . . . . . . . . . .Listing Public Properties . . . . . . . . . . . . . . . . . . . . . .Getting Property Values . . . . . . . . . . . . . . . . . . . . . .Setting Property Values . . . . . . . . . . . . . . . . . . . . . .15-1315-1315-1315-14Calling Object Methods . . . . . . . . . . . . . . . . . . . . . . . . .What Operations Can You Perform . . . . . . . . . . . . . .Method Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15-1515-1515-15xvii

Class of Objects Returned by Methods . . . . . . . . . . . .15-16Desktop Tools Are Object Aware . . . . . . . . . . . . . . . . .Tab Completion Works with Objects . . . . . . . . . . . . .Editing Objects with the Variables Editor . . . . . . . . .15-1815-1815-18Getting Information About Objects . . . . . . . . . . . . . . .The Class of Workspace Variables . . . . . . . . . . . . . . .Information About Class Members . . . . . . . . . . . . . .Logical Tests for Objects . . . . . . . . . . . . . . . . . . . . . .Displaying Objects . . . . . . . . . . . . . . . . . . . . . . . . . . .Getting Help for MATLAB Objects . . . . . . . . . . . . . .15-2015-2015-2215-2215-2315-24Copying Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Two Copy Behaviors . . . . . . . . . . . . . . . . . . . . . . . . .Value Object Copy Behavior . . . . . . . . . . . . . . . . . . .Handle Object Copy Behavior . . . . . . . . . . . . . . . . . .Testing for Handle or Value Class . . . . . . . . . . . . . . .15-2515-2515-2515-2615-29Destroying Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Object Lifecycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Difference Between clear and delete . . . . . . . . . . . . .15-3115-3115-31Defining Your Own Classes16Scripts and Functions17xviiiContentsScriptsCreate Scripts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17-2Add Comments to Programs . . . . . . . . . . . . . . . . . . . . . .17-4

18Run Code Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Divide Your File into Code Sections . . . . . . . . . . . . . .Evaluate Code Sections . . . . . . . . . . . . . . . . . . . . . . . .Navigate Among Code Sections in a File . . . . . . . . . . .Example of Evaluating Code Sections . . . . . . . . . . . . .Change the Appearance of Code Sections . . . . . . . . .Use Code Sections with Control Statements andFunctions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17-617-617-617-817-817-12Scripts vs. Functions . . . . . . . . . . . . . . . . . . . . . . . . . . .17-1617-12Function BasicsCreate Functions in Files . . . . . . . . . . . . . . . . . . . . . . . .18-2Add Help for Your Program . . . . . . . . . . . . . . . . . . . . . .18-5Run Functions in the Editor . . . . . . . . . . . . . . . . . . . . .18-7Base and Function Workspaces . . . . . . . . . . . . . . . . . . .18-9Share Data Between Workspaces . . . .

October 2004 Online only Revised for MATLAB 7.0.1 (Release 14SP1) March 2005 Online only Revised for MATLAB 7.0.4 (Release 14SP2) June 2005 Second printing Minor revision for MATLAB 7.0.4 September 2005 Online only Revised for MATLAB 7.1 (Release 14SP3) March 2006 Online only Revised for MATLAB 7.2 (Release 2006a)