"Function might be unused"

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Shelby Russ on 3 Dec 2016
Commented: Walter Roberson on 12 Apr 2021
I can't seem to figure our why Matlab doesn't like my function. It keeps telling me that it is probably called incorrectly but I can't see what I did wrong here.
Ideal Boiler Function
hfg=930
lhv=21500
p_percent=100
p=p_percent/100
MFfr=0.5191
%This function will calculate the steam mass flow rate (SMfr)
%of an actual boiler with 100% efficency (p_percent=100%)
%This funtion has 4 inputs (p,hfg,lhv,and MFfr),
%and 1 output (SMfr).
function SMfr=Ideal_Boiler(p,hfg,lhv,MFfr)
SMfr=(MFfr*p*lhv)/hfg;
output=SMfr;
end
disp('SMfr =');disp(SMfr)

bio lim on 3 Dec 2016
I don't see any problems, unless you defined the function inside your main script, and MATLAB doesn't allow that.
hfg=930;
lhv=21500;
p_percent=100;
p=p_percent/100;
MFfr=0.5191;
SMfr=Ideal_Boiler(p,hfg,lhv,MFfr)
disp('SMfr =');disp(SMfr)
SMfr =
12.0007
SMfr =
12.0007
Shelby Russ on 3 Dec 2016
Oh my gosh, thank you so much. I would have never figured that out.
bio lim on 3 Dec 2016
My pleasure. One more thing:
In your code, if you end a line with a semi-colom, i.e., ; , MATLAB doesn't print out the results. So in your code:
disp('SMfr =');disp(SMfr)
Is unnecessary, if you just end your function call, i.e., SMfr=Ideal_Boiler(p,hfg,lhv,MFfr) without a semi-colon (Meaning it will print the result out).

Kevin Agudo on 12 Apr 2021
syms t
function y = f(t)
t=linspace(0,100);
f(x)=(3*t^2+1)./(t^3+50);
h=.01;
plot(t ,(f(t+h)-f(t))./h,t,(f(t+h)-2*f(t)+f(t-h))/h^2)
end
When I run the function, dont get a graph and it says "function f may not be used"
Walter Roberson on 12 Apr 2021
h=.01;
t=linspace(0,100);
plot(t ,(f(t+h)-f(t))./h,t,(f(t+h)-2*f(t)+f(t-h))/h^2)
function y = f(t)
y=(3*t.^2+1)./(t.^3+50);
end