"Function might be unused"

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Shelby Russ
Shelby Russ 2016-12-3
评论： Walter Roberson 2025-2-28
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)

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采纳的回答

bio lim
bio lim 2016-12-3
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
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Shelby Russ
Shelby Russ 2016-12-3
Oh my gosh, thank you so much. I would have never figured that out.
bio lim
bio lim 2016-12-3
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).

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更多回答（2 个）

Kevin Agudo
Kevin Agudo 2021-4-12
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"
  1 个评论
Walter Roberson
Walter Roberson 2021-4-12
Ran in:
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

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Johanan
Johanan 2025-2-28
Adapt pend.m to build the double pendulum. A new pair of rod and bob must be defined for the second pendulum. Note that the pivot end of the second rod is equal to the formerly free end of the first rod: The (x, y) position of the free end of the second rod can be calculated by using simple trigonometry.
  1 个评论
Walter Roberson
Walter Roberson 2025-2-28
I do not understand how adapting pend.m will solve the problem of "Function might be unused" ???

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