Matlab basics II

Question 1

.mat

Answer 1

special data format in matlab; default data file type

Question 2

save

Answer 2

saves data from current matlab workspace to file
form: save(‘file_name’, ‘var1’, ‘var2’)
saves 1 or more variables: var1 and var2 in a file with the name file_name
default saves as .mat
can save in more general ascii format:
form: save(‘file_name.dat’, ‘var’, ‘-ascii’)

can also execute save in command form:
save file_name var1 var2
save file_name.dat var1 var2 -ascii

Question 3

load

Answer 3

Loads data from a disk file to the current MATLAB workspace:
load(‘file_name’)

Question 4

help

Answer 4

built in function; learn more about a specific function

Question 5

doc

Answer 5

brings out the help browser window where a more complete help menu about the function will be displayed

Question 6

log(x)

Answer 6

natural logarithm of x : lnx

Question 7

log10(x)

Answer 7

log base 10 x

Question 8

max(x), min(x)

Answer 8

find max, min values in the array x

Question 9

sum(x)

Answer 9

vector: sum of elements
matrix: gives a row vector with sum over each column

Question 10

sin(x)`vs sind(x)

Answer 10

gives sin of angle in radians vs. degrees

Question 11

sin(x) vs asin(x)

Answer 11

sin(x) vs arcsin (x)

Question 12

round(x)

Answer 12

rounds x to nearest integer

Question 13

floor(x)

Answer 13

rounds x to nearest integer towards negative infinity

Question 14

ceil(x)

Answer 14

rounds x to nearest integer towards positive infinity

Question 15

fix(x)

Answer 15

rounds x to nearest integer towards 0

Question 16

array operations

Answer 16

.* and ./
element-by-element (scalar) operations between two arrays of the SAME DIMENSION
a./b array right division, a/b
a.\b array left division. b/a

Question 17

zeros

Answer 17

used to assign value of 0 to a variable or an element/bunch of elements in a variable

Question 18

eye(n)

Answer 18

generates identity matrix of dimension (n,n)

ex. eye(3): 3x3 identity matrix

Question 19

syntax error

Answer 19

spelling errors, punctuation errors, wrong shape/size/type of input, unbalanced brackets
“Undefined function or variable…”
“arguments dimensions are not consistent”
“expression or statement is incorrect”

Question 20

Runtime error

Answer 20

found when function is executing

“exceeds matrix dimensions”

Question 21

Logical/Algorithmic error

Answer 21

function executes without error but does not produce the desired result

Question 22

debugging

Answer 22

set breakpoints to pause execution of matlab file; step through file

Question 23

subarrays

Answer 23

selections of subsets of elements in original array

Question 24

multidimensional array

Answer 24

can be created by putting lower dimension arrays together

multid_array(row_no,column_no,page_no,book_no,…)