Chapter 8, Input/Output Functions Video Solutions, MATLAB Programming for Engineers

02:41

Problem 1

What is the difference between binary and formatted $1 / O$ ? Which MATLAB functions perform each type of L/O?

Anatole Borisov

Numerade Educator

03:41

Write a MATLAB program to generate a table of the base-10 logarithms between 1 and 10 in steps of $0.1$. The table should start on a new page, and it should include a title describing the table and row and column headings. This table should be organized as shown below.

Willis James

Numerade Educator

05:12

Problem 3

Write a MATLAB program that reads in a time in seconds since the start of the day (this value will be somewhere between $0.0$ and $86400.0$ ), and prints a character string containing time in the form HH:MM: SS using the 24-hour clock convention. Use the proper format converter to ensure that leading zeros are preserved in the MM and ss fields. Also, be sure to check the input number of seconds for validity, and write an appropriate error message if an invalid number is entered.

Willis James

Numerade Educator

08:33

Problem 4

The acceleration due to the Earth's gravity at any height $h$ above the surface of the Earth is given by the equation
$$
g=-G \frac{M}{(R+h)^{2}}
$$
where $G$ is the gravitational constant $\left(6.672 \times 10^{-11} \mathrm{~N} \mathrm{~m}^{2} / \mathrm{kg}^{2}\right), M$ is the mass of the Earth $\left(5.98 \times 10^{24} \mathrm{~kg}\right), R$ is the mean radius of the Earth $(6371 \mathrm{~km})$, and $h$ is the height above the Earth's surface. If $M$ is measured in $\mathrm{kg}$ and $R$ and $h$ in meters, then the resulting acceleration will be in units of meters per second squared. Write a program to calculate the acceleration due to the Earth's gravity in $500-\mathrm{km}$ increments at heights from $0 \mathrm{~km}$ to $40,000 \mathrm{~km}$ above the surface of the Earth. Print out the results in a table of height versus acceleration with appropriate labels, including the units of the output values. Plot the data as well.

Kaitlin Coad

Numerade Educator

01:37

Problem 5

The program in Example $8.5$ illustrated the use of formatted $1 / O$ commands to read $(x, y)$ pairs of data from disk. This could also be done with the 1 oad -asci i function. Rewrite this program to use load instead of the formatted I/O functions. Test your rewritten program to confirm that it gives the same answers as Example 8.5.

Ankit Gupta

Numerade Educator

01:40

Problem 6

Rewrite the program in Example $8.5$ to use the textread function instead of the formatted $1 / O$ functions. How difficult was it to use textread, compared to using load -ascif or the formatted l/O functions?

Mayank Tripathi

Numerade Educator

10:06

Problem 7

Write a program that reads an arbitrary number of real values from a user-specified input data file, rounds the values to the nearest integer, and writes the integers out to a user-specified output file. Make sure that the input file exists, and if not, tell the user and ask for another input file. If the output file exists, ask the user whether or not to delete it. If not, prompt for a different output file name.

Darren Wilson

Numerade Educator

00:38

Problem 8

Table of Sines and Cosines. Write a program to generate a table containing the sine and cosine of $\theta$ for $\theta$ between $0^{\circ}$ and $90^{\circ}$, in $1^{\circ}$ increments. The program should properly label each of the columns in the table.

Ankit Gupta

Numerade Educator

08:07

Problem 9

Suppose that you have a sum of money $P$ in an interest-bearing account at a local bank ( $P$ stands for present value). If the bank pays you interest on the money at a rate of $i$ percent per year and compounds the interest monthly, the amount of money that you will have in the bank after $n$ months is given by the equation
$$
F=P\left(1+\frac{i}{1200}\right)^{n}
$$
where $F$ is the future value of the account and $\frac{i}{12}$ is the monthly percentage interest rate (the extra factor of 100 in the denominator converts the interest rate from percentages to fractional amounts). Write a MATLAB program that will read an initial amount of money $P$ and an annual interest rate $i$, and will calculate and wriv out a table showing the future value of the account every month for the next 5 years. The table should be written to an output file called "interest': Be sure to properly label the columns of your table.

Ernest Castorena

Numerade Educator

01:13

Problem 10

Write a program to read a set of integers from an input data file, and locate the largest and smallest values within the data file. Print out the largest and smallest values, together with the lines on which they were found. Assume that you do not know the number of values in the file before the file is read.

Sarvesh Somasundaram

Numerade Educator

03:43

Problem 11

We wrote a MATLAB program that calculated the arithmetic mean (average), rms average, geometric mean, and harmonic mean for a set of numbers. Modify that program to read an arbitrary number of values from an input data file, and calculate the means of those numbers. To test the program, place the following values into an input data file and run the program on that file: $1.0,2.0,5.0,4.0,3.0$, $2.1,4.7,3.0$.

Kajal Gautam

Numerade Educator

00:57

Problem 12

Angles are often measured in degrees $\left({ }^{\circ}\right)$, minutes $\left({ }^{*}\right)$, and seconds $\left({ }^{*}\right)$, with 360 degrees in a circle, 60 minutes in a degree, and 60 seconds in a minute. Write a program that reads angles in radians from an input disk file, and converts them into degrees, minutes, and seconds. Test your program by placing the following four angles expressed in radians into an input file, and reading that file into the program: $0.0,1.0,3.141593,6.0$.

Erika Bustos

Numerade Educator

00:58

Problem 13

Create a data set in some other program on your computer, such as Microsoft Word, Microsoft Excel, a text editor, etc. Copy the data set to the clipboard using the Windows or UNIX copy function, and then use function uimport to load the data set into MATLAB.

Ashley Volpe

Numerade Educator

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