how to plot number in legend ?

Question

tomer polsky 2018-4-6

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https://ww2.mathworks.cn/matlabcentral/answers/393172-how-to-plot-number-in-legend

评论： Walter Roberson 2018-5-14

he this is my code

for a=[ 1 3 5]
hold on;
disp('a')
H1=tf([ a],[3 4 ])
step(H1)
end

I want that in the plot it will be written the value of a of each line in the legend is it possible ?

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dpb 2018-4-6

Sure, just use num2str to write whatever text (if any) you want for each line label and pass to legend

tomer polsky 2018-4-7

编辑：tomer polsky 2018-4-7

image.png

hi thank you for your answer ,but what I meant that it will be like this :

but insted that it will be written in the legend manually it will be written outamtacly

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Answer 1

Walter Roberson 2018-4-7

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https://ww2.mathworks.cn/matlabcentral/answers/393172-how-to-plot-number-in-legend#answer_313876

在 MATLAB Online 中打开

avals = [ 1 3 5];
for a = avals
  hold on;
  disp(a)
  H1 = tf([ a],[3 4 ])
  step(H1)
end
legend( sprintfc('%g', avals) )

I think that your legend() call in your image has the wrong order. The larger the numerator in the transfer function, the more gain there should be, so the last a drawn, the 5, should be the last legend entry, but you have reversed the order.

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tomer polsky 2018-4-15

thank you very much for your help !!! bless you

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Answer 2

tomer polsky 2018-5-13

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/393172-how-to-plot-number-in-legend#answer_320032

Hi I have other question , how can I write "K=1" and not only "1" ?

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dpb 2018-5-14

编辑：dpb 2018-5-14

在 MATLAB Online 中打开

Hmmm....didn't notice but presumed tf something else as at least here

>> for a=[ 1 3 5]
hold on;
disp('a')
H1=tf([ a],[3 4 ])
step(H1)
end
a
Undefined function 'tf' for input arguments of type 'double'. 
>>

the xfr-function requires a digital filter object for input, not a double so OP may have something else of same name or older release or...???

>> which tf -all
C:\ML_R2017\toolbox\signal\signal\@dfilt\tf.m  % dfilt method
>>

Must admit haven't used it ever, though, since like R12 or thereabouts as gave up the consulting gig way back when so need went away...oldest release still at hand is R2014b and it's same need.

So, to OP--what is tf and what does step do to it??? I can't run what you have here to 'spearmint with--

Walter Roberson 2018-5-14

在 MATLAB Online 中打开

>> which tf(1)
/Applications/MATLAB_R2018a.app/toolbox/control/ctrlmodels/@tf/tf.m  % tf constructor

tf() is one of the primary routines for building transfer functions for control systems. step() with no output causes plotting of the transfer function.

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