# . Find a MATLAB built in function that is used to find the lowest common denominator of fractions.

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David Durost on 22 Aug 2019
Commented: Walter Roberson on 23 Aug 2019
Hello, I new to Matlab and I need help with this one problem.
"Find a MATLAB built in function that is used to find the lowest common denominator of fractions. Then use that function to show that the lowest common denominator of (hint, your input and solution will only contain one denominator values.'

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David Durost on 23 Aug 2019
I've already done a search and that is why I finally came here. I'm asking for help with writing the function.
Would it be something like L = lcm(A,B) or
builtin(function,x1,...,xn)[y1,...,yn] = builtin(function,x1,...,xn)?
Walter Roberson on 23 Aug 2019
The first of those. builtin() has some fairly specific uses. I have rarely had need for it.
David Durost on 23 Aug 2019
Okay, I 've tried
x=(1/4);
y=(1/10);
L=lcd(x,y);
and
L=lcd(4,10);
built in(function,4,10);
I would really appericate help with the syntax?

David Durost on 23 Aug 2019
I would say thanks however, 'com=1cm(d1,d2); is a Unexpected MATLAB expression. I don't appericate the concending remark of how easy this code is. It may be easy for you but not everyone can be a genious like you.

Star Strider on 23 Aug 2019
com=1cm(d1,d2);
Walter Roberson on 23 Aug 2019
lcm(4,10) is 20. What do you get when you multiply 1/4 by 20? How many 20'th is 1/4 ? What do you get when you multiply 1/10 by 20? How many 20'th is 1/10 ?
Walter Roberson on 23 Aug 2019
Be sure to distinguish between 'l' (lower-case L) and '1' (digit for the number One)

Walter Roberson on 23 Aug 2019
[n1, d1] = rat(1/4);
[n2, d2] = rat(1/10);
com = lcm(d1, d2);
Now that you have the least common multple of the denominators, you can calculate the equivalent fractions. The code is quite easy, but I will not provide it as you are obviously working on an assignment.