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# How to enter simple function for converting Fahrenheit to Celsius?

Asked by Ahmed Bilal on 9 May 2012

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

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Answer by Andrei Bobrov on 9 May 2012
```CelsiusToFahrenheit = @(c)c*9/5+32
```

eg

```>> CelsiusToFahrenheit(15)
ans =
59
```

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

```Fahrenheit(15)
```

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.

Ahmed Bilal on 9 May 2012

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

Walter Roberson on 9 May 2012

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

Fahrenheit(15)

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.

Andrei Bobrov on 9 May 2012

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

Walter Roberson on 9 May 2012

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;
CelsiusToFahrenheit(15)