Chapter 4: Programming in Matlab - College of the Redwoods

Section 4.5 Subfunctions in Matlab 387
second step of our hand calculation above. If the remainder b is zero, then a
is the GCD, which we assign to the output variable d, then issue a return.
3. Iterate until done.
Now that we have a function that will find the greatest common divisor, let’s
craft a function that will reduce a fraction to lowest terms.
Reducing to Lowest Terms. Our function will take as input the numerator
and denominator of the rational number. It will then call rationalGCD to find
the greatest common divisor of the numerator and denominator. It will then
divide both numerator and denominator by the greatest common divisor and
output the results. Open the Matlab editor, enter the following lines, then save
the file as rationalReduce.m.
function [num,den]=rationalReduce(num,den)
d=rationalGCD(num,den);
num=num/d;
den=den/d;
Let’s test this function on the fraction 336/60, which we know reduces to 28/5.
>> [num,den]=rationalReduce(336,60)
num =
28
den =
5
This is the correct response. The calling script of function will need to take
responsibility for formatting the output.
Adding Subfunctions to Primary Function. We’ve tested rationalGCD
and rationalReduce and found them to produce the correct results. We will
now add each of these functions as subfunctions to our existing primary function
rationalArithmetic. Open the file rationalArithmetic and add the following
lines at the very bottom of the file rationalArithmetic.m.
function [num,den]=rationalReduce(num,den)
d=rationalGCD(num,den);
num=num/d;
den=den/d;