Symbolic Expression Sum Same Denominator

I have a symbolic experssion in the form: (where are symvars)

(3*a)/8 + (3*b)/8 + c/4

I would like this to be in the form of the same denominator, like:

(3*a + 3*b + 2*c) / 8

How can I achieve this ?

Answer 1

[Star Strider]

Try this:

syms a b c 
Eqn = (3*a)/8 + (3*b)/8 + c/4
[Eqnn,Eqnd] = numden(Eqn)

producing:

Eqnn =
3*a + 3*b + 2*c
 
Eqnd =
8

Unfortunately, if you express it again as:

NewEqn = Eqnn / Eqnd

the result is the original format for ‘Eqn’.

EDIT —

The best you can hope for is a LaTeX expression for your fraction:

syms a b c 
Eqn = (3*a)/8 + (3*b)/8 + c/4
[Eqnn,Eqnd] = numden(Eqn)
fn = latex(Eqnn);
fd = latex(Eqnd);
Expr = sprintf('$f(a,b,c) = \\frac{%s}{%s}$', fn, fd)

producing:

Answer 2

[madhan ravi]

simplifyFraction()

syms a b c 
eqn = (3*a)/8 + (3*b)/8 + c/4
simplifyFraction(eqn,'Expand',1) % the best way to simplify a fraction by expanding also returns the same 

[Miraç Gülgönül]

I don't understand, this outputs

eqn =
 
(3*a)/8 + (3*b)/8 + c/4
 
 
ans =
 
(3*a)/8 + (3*b)/8 + c/4

so no change.

[madhan ravi]

Yes exactly matlab is not able to compute those fractions as you desire.

Try:

bb=factor(eqn)  % gives your partial result though

Gives:

bb =
 
[ 1/8, 3*a + 3*b + 2*c]