MATLAB Answers

Ahmed Bilal

How to enter simple function for converting Fahrenheit to Celsius?

Asked by Ahmed Bilal
on 9 May 2012
Latest activity Commented on by Walter Roberson
on 27 Nov 2015

Hi All

I am trying to write a simple function for change of temperature from Fahrenheit to Celsius but i could not. I have been trying to do it from last about 4 hours, and it drives me almost crazy... well what i wrote in m file is

function f = Fahrenheit(c)
% gives temp in Fahrenheit
%converts Celcius to Fahrenheit
f = c*9/5+32

But when i try to run it the commend window gives following error

??? Input argument "c" is undefined.
Error in ==> forenheit at 4
f = c*9/5+32

I am unable to figure out where is the problem. Whereas I have just written two other simple functions successfully. But this one and and another one for calculation of area of circle are not working at all. I shallbe really thankfull for any help



No products are associated with this question.

4 Answers

Answer by Andrei Bobrov
on 9 May 2012

CelsiusToFahrenheit = @(c)c*9/5+32


>> CelsiusToFahrenheit(15)
ans =


Answer by Walter Roberson
on 9 May 2012

You need to store your function in Fahrenheit.m . You currently have it stored in forenheit.m

You cannot run the program by pressing F5. Instead, at the MATLAB command line, you need to call the routine as a function. To use Andrei's sample value, at the command line type in


Later when you get the above working, you will need to recode the problem, as your current code converts Celsius to Fahrenheit, whereas your problem description indicates you need to convert the other way around.


Thank you for you help but still it gives following error
??? Input argument "c" is undefined.

Error in ==> Fahrenheit at 4

f = c*9/5+32

I think the main problem is in input argument "c" I do not know how to define it as the command window is asking

How _exactly_ are you running your code? You need to go into the command window and invoke


That will temporarily assign the value 15 to c while it runs the code.

If that does not work, please copy your exact current code to here.

Answer by Ahmed Bilal
on 9 May 2012

@andrei bobrov

Sorry but your answer is not working. When i replaced "c*9/5+32" with "@(c)c*9/5+32" as told by you and when i run the function in command window it returns simply "@(c)c*9/5+32" instead of any value.


use code in Command Window:
>> CelsiusToFahrenheit = @(c)c*9/5+32
>> CelsiusToFahrenheit(15)

The syntax

CelsiusToFahrenheit = @(c)c*9/5+32

defines "CelsiusToFahrenheit" as a function that does the required conversion work. Just type into the command window the two lines

CelsiusToFahrenheit = @(c)c*9/5+32;

Answer by R ALsabei
on 27 Nov 2015

Create a MATLAB user defined function called Temperature to calculate T in C and F degree.

  1 Comment

That does not appear to be a question, it appears to be a command. It is also an unclear command as it does not describe what the inputs are that need to be calculated in C and F degree.

Join the 15-year community celebration.

Play games and win prizes!

Learn more
Discover MakerZone

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn more

Discover what MATLAB® can do for your career.

Opportunities for recent engineering grads.

Apply Today

MATLAB Academy

New to MATLAB?

Learn MATLAB today!