清空筛选条件
清空筛选条件

How can I get a sinc function like this?

4 次查看（过去 30 天）
payman khayree
payman khayree 2014-9-7
评论： Image Analyst 2014-9-8
As we know there is a sinc function in matlab which calculates the sinc of the data. But I need to
get a sinc function that look like the image.
what mathematical properties should I change to turn the standard sinc function into one like this?
  6 个评论
显示 4更早的评论
Image Analyst
Image Analyst 2014-9-8
Perhaps, but not that I know of. Where did you see it? Did that place give a name for it? (I guess not otherwise you wouldn't be asking us.) It sort of looks like a sinc squared (the diffraction pattern of a thin slit, or a sombrero function (the optical diffraction pattern of a small circular aperture). Search sombrero or the cross section of a see this Wikipedia article
payman khayree
payman khayree 2014-9-8
I got this figure in the imaginary part of the fourier transform of the white/black square image:
there is white/black border in the 50th column of this 400*400 matrix.
I turned it into the image above because I wanted to see if I can make it similar to a sinc function.

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Image Analyst
Image Analyst 2014-9-8
This is about the closest I could get after playing around with it for a few minutes:
x = 1:400;
y = abs(0.055 * sinc((x - 195) / 12)) - 0.001;
% Smooth out a bit
y = conv(y, [1,1,1]/3, 'same');
plot(x, y, 'b-', 'LineWidth', 3);
grid on;
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off')
Why do you need this, and if you need it, why don't you have the formula for it? Where did you hear of it? Didn't they give you the formula?????
  5 个评论
显示 3更早的评论
payman khayree
payman khayree 2014-9-8
you are right. multiplying the function with an envelope might give the same result. But defining the properties of the envelope (at least for me) wont be easy.
Image Analyst
Image Analyst 2014-9-8
No, not easy if you have to just do trial and error. But if you don't have something known, then how do you know if your formula has gotten it right? And if you do have something knonwn, whether numerical data or a formula, then just use it.

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Multirate Signal Processing 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by