Figure but no plot

2020 12 2
2 个回答
更新时间：2020 12 2
4 次查看（30 天）

0 个投票

The code has no errors but won't show a plot, what am i doing wrong?
clear all, close all, clc
diffmax=100
x=0;0.1;diffmax
plot(f(x))
hold on
xlabel('x')
ylabel('velocity')
axis([0 diffmax 0 30])
function velocity=f(x)
if x>75
velocity = 25;
else
velocity = x/3;
end
end

1 个评论
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Clara Holmén
Clara Holmén 2020-12-2
I have now changed the code bc the slope that was plotted was wrong. I created a matrix y to plot against x, instead of calling the function in plot(f(x). However the plot then disappeared again..
I have colons for x this time, have i missed something else?
clear all, close all, clc
matris=[]
diffmax=100
x=0:diffmax
for i=1:diffmax
y=f(x(i))
matris=[matris;y]
end
plot(x, y)
hold on
xlabel('x')
ylabel('velocity')
axis([0 diffmax 0 30])
function velocity=f(x)
if x>75
velocity = 25;
disp('rad 18')
else
velocity = x/3;
disp('rad 21')
end
end

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回答（2 个）

KSSV
KSSV 2020-12-2

0 个投票

You have not defined f in your code...you need to define f and then call plot...something like this:
diffmax=100
x=0:0.1:diffmax ;
f = @(x) sin(x)
plot(x,f(x))

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Clara Holmén
Clara Holmén 2020-12-2
Thank you for the quick answer!
So it is not enough to have f as a function of x and have x defined??
KSSV
KSSV 2020-12-2
If you have defined an anonymous function (like in the answer), then you have to substitue it to get the function values for the given inputs.
Clara Holmén
Clara Holmén 2020-12-2
ok ill try it!
KSSV
KSSV 2020-12-2
Ran in:
Ran in:
clear all, close all, clc
diffmax=100
diffmax = 100
x=0:0.1:diffmax
x = 1×1001
0 0.1000 0.2000 0.3000 0.4000 0.5000 0.6000 0.7000 0.8000 0.9000 1.0000 1.1000 1.2000 1.3000 1.4000 1.5000 1.6000 1.7000 1.8000 1.9000 2.0000 2.1000 2.2000 2.3000 2.4000 2.5000 2.6000 2.7000 2.8000 2.9000
●
plot(f(x))
hold on
xlabel('x')
ylabel('velocity')
axis([0 diffmax 0 30])
function velocity=f(x)
if x>75
velocity = 25;
else
velocity = x/3;
end
end

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KALYAN ACHARJYA
KALYAN ACHARJYA 2020-12-2
编辑：KALYAN ACHARJYA 2020-12-2

0 个投票

Here is the issue, the rest code is perfectly OK
x=0:0.1:diffmax
%..^ ..^ not semicolon, its colon

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KSSV
KSSV 2020-12-2
Note that there is no f defined in the code.
KALYAN ACHARJYA
KALYAN ACHARJYA 2020-12-2
编辑：KALYAN ACHARJYA 2020-12-2
Sir, I dont think it is required, as f as function call within plot command. Can you share more please? Thanks
Clara Holmén
Clara Holmén 2020-12-2
i have semicolons in my code, this snippet is from the answer from KSSV!
KALYAN ACHARJYA
KALYAN ACHARJYA 2020-12-2
编辑：KALYAN ACHARJYA 2020-12-2
@Clara Replace with colon in your original code, I have tried to answer this "
Figure but no plot
KSSV
KSSV 2020-12-2
Ohh yes, the function f is defined at the bottom. Just now I am having a look...I have copied only the first few lines..as the problem was in first line.
Clara Holmén
Clara Holmén 2020-12-2
Sorry i misunderstood. It worked, thank you very much!!
KALYAN ACHARJYA
KALYAN ACHARJYA 2020-12-2
Hope your problem is resolved anyway.
Happy :)

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