MATLAB basic operations

As stated earlier, Matlab s philosophy is to read everything as a matrix. Consequently, the basic operators for multiplication, right division, left division, power (, /,, A) automatically perform corresponding matrix operations (A will be introduced shortly in the context of square matrices, / and will be discussed later, in the context of linear regression and the calculation of a pseudo inverse, see The Pseudo-Inverse, p.117). 

In contrast to Matlab, where the defaults are the matrix operators, in Excel the default is the element-wise operation. In fact, all basic operations (e-g- 0, 0> 0> 0> Q) and functions (e.g. EXP, LN, LOG) work element-wise in Excel. All... 

As we have said before, en eers use formulas that represent physical and chemical laws governing our surroundings to analyze various problems. You can use MATLAB to input engineering formulas and compute the results. When typing your formula, use parentheses to dictate the order of operation. For example, in MATLAB s Command Window, if you were to type count=100+5 2, MATLAB will perform the muldplication first, which results in a value of 10, and then this result is added to 100, which yields an overall value of 110 for the variable count. If, however, you wanted MATLAB to add the 100 to 5 fiist and then multiply the resulting 105 by 2, you should have placed parentheses around the 100 and 5 in the following manner count=(100+5) 2, which results in a value of 210. The basic MATLAB arithmetic operations are shown in Table 15.3. 

Usually, imaging workstations and luminometers include proprietary software to operate the devices and allow the direct export of raw data and basic measurements to common spreadsheet software, including Microsoft Excel. More complex image analyses can be successfully performed with ImageJ or Matlab software packages. 

Once in the ALATLAB environment, you can assign values to a variable or define the elements of a matrix. For example, as shown in F%ure 15.2, to ass a value of 5 to the variable X, in the Command Window after the prompt sign you simply type x = 5. The basic MATLAB scalar (arithmetic) operations are shown in Table 15.1. 

As we said at the b inning of thb chapter, there are many good textbooks that discuss the capabilities of MATLAB to solve a fijll range of problems. Here, our intent was to introduce only some basic ideas so diat you can perform some essential operations. As you continue your engineering education in other classes, you will learn more about how to use MATLAB eflfec-tively to solve a wide range of engineering problems. 

The layout of MATLAB can be seen in Figure 4.1. There are a number of different layouts that the user can define, see Layout Tab. We select one basic layout that consists of the workspace, in the figure to the left top corner, where the variables are stored a command history, to the right bottom corner, where a log of operations is stored and the command window, where calculations can be executed. 

Apart from performing operations, MATLAB is a programming language. Its operation is based on the use of. m files that can be divided in two classes, scripts and functions. A script is basically a number of operations that we want to perform in a certain sequence. It is required that they are in order so that the variables and parameters are already defined. We can use them as executables and within them, we can also call other subrogate scripts that contain other operations... 

To understand the concepts of the methods described in the following chapters, one should have an understanding of the basics of linear algebra. This chapter will serve as a short refresher. Linear algebra essentially deals with vector and matrix manipulations, all of which can easily be performed by using the MATLAB software. However, an insight into some of the concepts behind the operations may be helpful. 

Emphasis in Chapter 3 is placed on elementary methods, mostly used in arithmetic operations. Basic applications with many examples are presented, using MATLAB and Excel. We may call this is the fundamental part in numerical analysis. 

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