MATLAB, writing conditional statements

f(x) = { 2x^2 for -6 ≤ x ≤ -2
e^3x for -2 ≤ x ≤ 2.5
ln(2x) for 2.5 ≤ x ≤ 6 }

(this is just a made up example question, so that you're not helping me directly do my coursework ^^)

so. I need to use a CONDITIONAL STATEMENT in MATLAB to evaluate these ...

roughly how do i do it XD

Thanks!! I will rep the first most helpful anser at 00:00 :smile:

Reply 1

Kittyyyyyyy

Get yourself an m file, and put in something like this:
x=input (‘Enter a value for x - ’)
while x>=-6 && x<=-2
f(x)= 2x^2
if x>=-2 && x<=2.5
f(x)=e^3*x
elseif x>=2.5 && x<=6
f(x)=ln(2*x)

Possibly? I'm a matlab noob and don't have it on this computer...haha.

Reply 2

TheNack

Kittyyyyyyy

Get yourself an m file, and put in something like this:
x=input (‘Enter a value for x - ’)
if x>=-6 && x<=-2
f= 2*x^2
elseif x>=-2 && x<=2.5
f=e^3*x
elseif x>=2.5 && x<=6
f=ln(2*x)
else
f=0
end

Possibly? I'm a matlab noob and don't have it on this computer...haha.

Just fixed the parts in bold for you. The WHILE loop isn't necessary, and you were missing the 'end' from the IF loop. I also added the additional statement at the end that will make f=0 if x is outside the values defined and made the variable f where you put f(x). Putting f(x) willl tell matlab to put the value into index x in array f, which isn't what you want to do.