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BMEN.1200 BME Application Programming

Data & Plotting (Chapter 1+5)

Introduction

  • Overview of MATLAB and Knovel introduced

  • Introduction to data types in MATLAB

Agenda

  • Recap Previous Material

  • Diving Deeper into Data Types

    • Ranges of Numeric Data Types (integers and floats)

    • whos function for data type bookkeeping

    • Displaying Data using disp()

    • Data Type Casting

    • Boolean Examples

    • Loading and Saving Data

  • Activities 1.4 - 1.5, 5.2, and 5.5 from the chapter text

Key Data Types

Variable Types

  • Floating Point: e.g., 1.234 (single, double depending on precision)

  • Integer: e.g., 3 (int8, int16, int32, int64 based on storage bits)

  • Character: e.g., 'a' (char)

  • Boolean: e.g., true (logical)

Arrays and Matrices

  • Data Structure

    • Scalar, array, and matrix variables

    • 1D arrays called vectors in MATLAB

  • Array Operations

    • MATLAB allows element-wise operations: e.g., c = 2; d = [1 3 4 2 5];

    • Different operations: d + 3, d.^3, d.*e

Creating Arrays

  • Methods

    • Using colon operator: x = 1:100;

    • Using linspace: x = linspace(start, end, number of values);

Accessing and Displaying Arrays

  • Accessing Elements

    • Syntax: array(index)

    • Example: d(3) or setting value d(3) = 0

  • Displaying Data

    • Use disp(X) to display arrays

    • Example: disp(y);

Code Hygiene

Commenting

  • Multi-line comments: %{...%}

  • Single line comments: %

Suppressing Code

  • Use semicolons to suppress output and improve performance

Help Functions

  • Use the help command for function usage:

    • Example: help blank

Data Types in MATLAB

  • Common Types

    • Floating Point, Integer, Boolean, Character, Strings

  • Use whos to review variable types and sizes

    • Example: whos a b c

Numeric Types

Fundamental Numeric Types

  • Two main types:

    • Integers (unsigned & signed)

    • Floating point (single precision: 32 bits; double precision: 64 bits)

Floating-Point Arithmetic

  • Common issues due to finite precision in computers

  • Example code operations: sqrt(a) with different types

Converting Between Types

  • Various casting methods:

    • Between Number and Character

    • Between Number and Logical

  • Safer to use explicit function calls for conversions

Especial Values

  • Inf: Represents infinity

  • NaN: Represents 'Not a Number'

  • Test functions: isinf() and isnan() for identification

Loading and Saving Data

  • Use dlmwrite for writing arrays to text files

  • Load and save workspace components:

    • Example operations: save('newdata.mat'...)

Homework Assignments

  • Complete exercises from Chapters 1-5:

    • HW1 due September 17

    • Exercises 1.1 - 1.4, 5-8, 12-15, and Chapters 27-28