Question

matlab

Answer 1

On homework 5, problem 6.15 part c is my question

Answer 2

ignore 6.10

Answer 3

Is this part c)
% (c) Create a function called C_to_F that converts temperature in Celsius
% to Fahrenheit. Use your function to generate a conversion table from 0T*
% to 100* C. Choose an appropriate spacing.

Answer 4

% (c) Recall that you will need to call your primary function from the
% command window or from a script M-file.

Answer 5

^That is part C

Answer 6

you are looking at 6.10.

Answer 7

%% 6.15 In Problem 6.10 you were asked to create and use three different
% temperature conversion functions, based on the following conversion
% equations:
% Tf = Tr - 459.67 degrees R
% Tf = 9/5*Tc + 32 degrees F
% Tr = 9/5*Tk
% Recreate Problem 6.10 using nested subfunctions. The primary function
% should be called temperature_conversions and should include the
% subfunctions
% F_to_k
% C_to_R
% C_to_F
% Within the primary function use the subfunctions to:

clc; clear % clears command and workspace window

% (a) Generate a conversion table for values from 0*F to 200*F. Include a
% column for temperature in Fahrenheit and Kelvin.

Tf = 0:200; % Fehrenheit vector from zero to two-hundred
c6p15a1 = temperature_conversions1(Tf); % c6p15a1 = temp_conv1 which finds temp. conversions
c6p15a2 = temperature_conversions2(Tf); % c6p15a2 = temp_conv2 which finds tem. conversions
c6p15a3 = temperature_conversions3(Tf);

conv_table1 = [Tf; c6p15a1]' % table displays fahrenheit in col_1 and kelvin in col_2
conv_table2 = [Tf; c6p15a2]' % table displays fahrenheit in col_1 and rankine in col_2
conv_table3 = [Tf; c6p15a3]' % table displays fahrenheit in col_1 and fahrenheit in col_2


% (c) Recall that you will need to call your primary function from the
% command window or from a script M-file.

Answer 8

I don't know much about matlab. Let me check google.

Answer 9

@hartnn

Answer 10

define a file C_to_F.m that contains:

% f= function C_to_F(c)
% input: temperature in degrees Celcius
% returns temp in Fahrenheit
function f= C_to_F(c)
f= (9/5).*c+32;

now you can use this function to create a table. Example:

>> cc=0:5:100; % degrees Celcius
>> ff= C_to_F(cc); % convert to Fahrenheit
>> str=sprintf('%4dº C %4.0fº F\n', [cc; ff]); disp(str);
0º C 32º F
5º C 41º F
10º C 50º F
15º C 59º F
20º C 68º F
25º C 77º F
30º C 86º F
35º C 95º F
40º C 104º F
45º C 113º F
50º C 122º F
55º C 131º F
60º C 140º F
65º C 149º F
70º C 158º F
75º C 167º F
80º C 176º F
85º C 185º F
90º C 194º F
95º C 203º F
100º C 212º F

Answer 11

@phi

Answer 12

Can I just use the C_to_F file i already made for problem 6.10?

Answer 13

% (c) Recall that you will need to call your primary function from the
% command window or from a script M-file.

Answer 14

^This is what I need to answer.

Answer 15

does your C_to_F work ?

Answer 16

I would make sure your functions accept vectors of numbers
use .* instead of *

Answer 17

my C_to_F works just fine for pobelm 6.10. I am just trying to figure out how to use it for part C of problem 6.15

Answer 18

or do I need to make a new m file. I could call it CC_to_FF

Answer 19

Here is my C_to_F code

function C_to_F = CF(f)

% this function converts from degrees celsius to degrees fahrenheit
C_to_F = (5 / 9) * f - 32;
end

Answer 20

your syntax is off (though I think matlab will allow it)
I would write it
function f = C_to_F( c )
notice I named the input "c" to remind us it is celsius
and the output is f (for fahrenheit)
and the name of the function is C_to_F and not CF

Answer 21

I see what you are saying, but matlab will accept this function C_to_F = CF(f)

Answer 22

yes, but you really should use C_to_F as the name of the function (and the name of the .m file)
and it is confusing to someone who reads "f" as an input. (They will think the input is in degrees fahrenheit)

Answer 23

Oh okay I will change that. Let me think about this a bit more

Answer 24

@phi

You have to leave it this way in order for it to run..
function C_to_F = CF(c)

% this function converts from degrees celsius to degrees fahrenheit
C_to_F = (5 / 9) * c - 32;
end

Answer 25

what I tried to do is change it to

function CF = C_to_F(c)

CF = (5/9)*c-32
end

Answer 26

^But it won't run. the C_to_F = CF(), the C_to_F has to match the m file name, not next to the parenthesis

Answer 27

yes, but you want the file name to match the function name.

>> cc=0:5:100; % degrees Celcius
>> ff= C_to_F(cc); % convert to Fahrenheit

Answer 28

it is "good form" ... otherwise your code will be confusing to anybody else (and possibly even to you at a later time)

Answer 29

so in this case my file name would be ff

Answer 30

the question is
% (c) Create a function called C_to_F that converts temperature in Celsius

to me, that means create a file named C_to_F.m
and in that file you have
function f= C_to_F©
stuff....

Answer 31

I see what you are saying, but in matlab it will throw an error if you code it this way. That is what I am trying to say

Answer 32

the f has to be C_to_F in order to run it.

Answer 33

At first I thought the function part was after the equals sign, but while doing this assignment it proved me wrong.

Answer 34

I don't think so.

try this: create a file
C_to_F.m
put in
% f= function C_to_F(c)
% input: temperature in degrees Celcius
% returns temp in Fahrenheit
function f= C_to_F(c)
f= (9/5).*c+32;


then in the matlab command line, clear it, clear; clc
then type
>> cc=0:5:100; % degrees Celcius
>> ff= C_to_F(cc); % convert to Fahrenheit
>> str=sprintf('%4dº C %4.0fº F\n', [cc; ff]); disp(str);

Answer 35

give me a sec

Answer 36

let me fix the comment:
% f= C_to_F(c)
% input: temperature in degrees Celcius
% returns temp in Fahrenheit
function f= C_to_F(c)
f= (9/5).*c+32;
end;

(It is good to remind the user what the input and output are in the comments at the head of the file. Then if you type
>> help C_to_F
you will get those comments.

Answer 37

function f= C_to_F(c)
↑
Error: Function definitions are not permitted in this context.

Answer 38

you have to put that in a separate file with nothing else in the file.

Answer 39

give me a sec

Answer 40

So I need to put C_to_F in a separate file with nothing else?

Answer 41

So I made a new file and placed C_to_F in it and ran the code. I get an error.

Answer 42

I thought the file has to be in the same file as my "homework5" in order to run.

Answer 43

what is the error?

Answer 44

Undefined function or variable 'C_to_F'.

Answer 45

this is the problem you had in the past. If you do
>> dir
do you see your file ?

Answer 46

>> dir

. Homework5.asv if else.m ~$govt_camp.xlsx
.. Homework5.m temperature_conversions1.m
Ex. problems textbook Matlab HW temperature_conversions2.m
F_to_K.m Matlab labs temperature_conversions3.m

Answer 47

I had it in this file, but then I removed it like you told me to

Answer 48

the C_to_F.m file should be in the directory.

Answer 49

okay it runs. So why was it running before?

Answer 50

It was probably running incorrectly

Answer 51

I usually put all my functions into their own .m file (one function to a file)

I know you can put multiple functions in a file, but rarely do that.

Answer 52

Okay, I am going back to change the variables so it's so confusing.

Answer 53

@jim_thompson5910

Answer 54

@jim_thompson5910

Answer 55

% (c) Recall that you will need to call your primary function from the
% command window or from a script M-file.

Tc = 0:5:100; % Celsius vector from zero to one-hundred
c6p10c = C_to_F(Tc); % outputs fahrenhiet for every celcius input

% creates a table with values of celcius in colum_1 and fahrenheit in
% colum_2
table_C_F = fprintf('%4.0dº C %4.0fº F\n', [Tc; c6p10c]);

Answer 56

what's your question?

Answer 57

6.15 part c

% (c) Recall that you will need to call your primary function from the
% command window or from a script M-file.

Answer 58

my solution...


Tc = 0:5:100; % Celsius vector from zero to one-hundred
c6p10c = C_to_F(Tc); % outputs fahrenhiet for every celcius input

% creates a table with values of celcius in colum_1 and fahrenheit in
% colum_2
table_C_F = fprintf('%4.0dº C %4.0fº F\n', [Tc; c6p10c]);

Answer 59

how is the table turning out?

Answer 60

º C -32º F
5º C -29º F
10º C -26º F
15º C -24º F
20º C -21º F
25º C -18º F
30º C -15º F
35º C -13º F
40º C -10º F
45º C -7º F
50º C -4º F
55º C -1º F
60º C 1º F
65º C 4º F
70º C 7º F
75º C 10º F
80º C 12º F
85º C 15º F
90º C 18º F
95º C 21º F
100º C 24º F
>>

Answer 61

strange. 100 C is not equal to 24 F

Answer 62

0 C = 32 F
100 C = 212 F

Answer 63

that isn't good because my C_to_F function for problem 6.10 spits out 23.5556 for 100* C

Answer 64

you're using

F = (9/5)*C + 32

right?

Answer 65

or

F = 1.8*C + 32

which is equivalent just in decimal form instead of fraction form

Answer 66

no i am using

F = (5/9)*c-32

Answer 67

you're mixing that up with

C = (5/9)*(F - 32)

Answer 68

100 => 212

Answer 69

F = (9/5)*c+32;

Answer 70

so for 100* C I get 212* F

Answer 71

much better

Answer 72

so since my instructor wants to only see the function m files how am I suppose to show him that I did part c of problem 6.15 ?

Answer 73

He doesn't want the homework5.m file which is strange because that m file has a huge chunk of my hw.

Answer 74

can i see the pdf where your teacher gives the instructions?

Answer 75

yeah give me a sec

Answer 76

Formatting too. I am a little confused if I need clear, clc in function m files or not. I emailed him about formatting because I am still a bit confused. He hasn't responded. The homework is due at 10pm .

Answer 77

on your hw formatting requirements it says
`Unless there is a reason not to, begin each problem with the clear and clc commands`

so I'd have clc and clear

Answer 78

on each function m file?

Answer 79

you do not need clc or clear in the function files. The top of the function file should be the line setting up the main function

`function [output1,output2,...,outputN] = name(input1,input2,...,inputN)`

Answer 80

the reason why you don't need `clc` in a function file is because the function should not show anything to the command window. That's the job of the m file that calls the function

You don't need `clear` either because each variable in the function is a local variable that is only accessible to the function. The only thing that the m file (that calls the function) can touch is the output variables of the function. But those values will be cleared by the m file

Answer 81

okay, good to know.

Answer 82

I think that is all the questions I have now and will be submitting the assignment.

Answer 83

btw, each time the function starts, the local variables are set up in memory. At first, just blank slots

then the local variables get values in them

when the function ends, the output variables return to the script function. This is when the function will delete and deallocate the local variables in memory

Answer 84

so in a way, the function is using `clear` so another reason why you don't need it

Answer 85

btw i can't get
%( blah blah blah

%) to work

Answer 86

http://www.mathworks.com/matlabcentral/answers/122-how-do-i-comment-out-a-large-block-of-code-in-matlab

someone is saying

`% {`
`commented stuff`
`%}`

Answer 87

hmmm interesting

Answer 88

you can also select the text and do a block comment

Answer 89

% {
commented stuff
%}

it doesn't work.. How do I block comment? Is there a button in matlab?

Answer 90

should be in the edit dropdown menu

Answer 91

your version is different from mine

Answer 92

I don't see it. I am not too worried about it. So what about part c on problem 6.15. I am going to basically have to turn in homework5 to show my instructor I did problem 6.15, part C?

Answer 93

you probably have a version older than version R14

Answer 94

if your teacher hasn't gotten back to you, I would turn in hw5.m just in case. I know it says not to, but it seems odd how you do all that work but not turn it in