sinc + cos function plot
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Respectively, codes, matlab plot, and graphing site plot.
Even though I made same argument, matlab plot gives wrong plot. What's wrong? I need your help.
3 个评论
Walter Roberson
2023-5-13
The graphing site is clearly wrong: the red curve is just sinc() without any cos() component.
James Tursa
2023-5-13
Please post code as regular text highlighed by the CODE button. We can't run images.
민건 김
2023-5-13
采纳的回答
Delete pi from below line
% delete pi from the below line
a = (-4:0.001:4);
p = 10;
f = p*sinc(a) + cos(a)
plot(a,f)
5 个评论
민건 김
2023-5-13
The cos still needs the pi
a = (-4:0.001:4)*pi;
p = 10;
f = p*sinc(a/pi) + cos(a)
plot(a,f)
By definition sinc can be written as (sinx / x) , so if you apply in the equation, you would get a result as shown below,
% delete pi from the below line
a = (-4:0.001:4)*pi;
p = 10;
f = p*sin(a)./a + cos(a)
plot(a,f)
In your code, you have multiplied or included pi in x-vector, but did not divide it. The graph which you want to obtain is actually sin(pi*x)/ (pi*x)
Note however
x = 0
sinc(x)
sin(x)./x
"By definition sinc can be written as (sinx / x) "
Except in the field of digital signal processing where it is commonly defined as
sin(pi*x) / (pi*x)
which is the definition that SINC uses, SINC being part of the Signal Processing toolbox:
"In the context of digital signal processing, we often use an alternative form in which the independent variable is multiplied by π":
" The sinc function is defined as: sinc(a) = sin(πa)/(πa)":
See also the note given here: https://numpy.org/doc/stable/reference/generated/numpy.sinc.html
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