Mathematics, Chalmers University of Technology and Göteborg University

#### Matlab exercise 1

(written by Kenneth Eriksson, modified by Stig Larsson)

Arithmetic:

>> 7+9

>> 3*2

>> 2(3+4)

>> 2+3*4

>> (2+3)*4

>> 2^3

>> 21/7

>> ans*2

>> 3,14

>> 3.14

>> pi

>> 2/3

>> format long

>> 2/3

>> pi

>> round(ans)

>> ceil(3.1)

>> floor(3.1)

>> help

>> help ops

>> helpwin

>> helpdesk

Exercises:

1. Compute the sum of the product of 3 and 4 and the difference between 9 and 3.

2. Convert the binary numbers 10010000 and 1111111111 to the decimal form. Hint: use 2^j.

3. Use helpwin or helpdesk to find a matlab command that does the conversion in previous exercise. Hint: search for binary.

4. Express pi rounded to 3 decimals. Hint: round 1000*pi.

=================

Variables:

>> a=3

>> b=5; (What is the effect of ; here?)

>> b

>> c=a+2*b;

>> c=c+1

>> c=a*d;

>> base=3

>> height=5

>> area=base*height/2

>> a_minus_b=a-b

>> who

>> whos

>> help who

>> help whos

>> clear

>> who

==================

Vectors/lists:

>> v=[4 1 7 5]

>> v(3)

>> v(3)=8

>> v(5)

>> w=[1 2 3 4]

>> v+w

>> v-w

>> v+1

>> 2*w

>> w/4

>> sum(w)

>> v*w

>> v.*w

>> w.^2

>> [v w]

>> ans'

>> u=1:4

>> u=0:2:10

>> u=0:3:9

>> u=0:3:10

>> u=0:.2:.6

>> u(2:3)

>> help linspace

>> linspace(0,1,6)

Exercises:

1. Define a price list for magazines, movie, cd, and a corresponding list of how many of these items you consume during a year. Then use these lists to compute a list of the total cost for each of the three items and the total cost.

2. Test whether 1+2+3+..+N ~= N^2/2 and 1+2^2+3^2+..+N^2 ~= N^3/3. Hint: first define x=1:N and use sum. What does ~= mean?

======================

Matrices:

>> m=[1 2 3; 4 5 6]

>> m(2,1)

>> m(1,3)

>> m(1,3)=7

>> v

>> w

>> [v;w]

>> v'

>> ans(3)

>> w'

>> [v' w']

>> ans'

>> [v';w']

>> who

>> help save

>> save junk

>> clear

>> who