Could you help me with FUNCTION syntax

Hi, could you help me please, how to make a function - for example
function [xx,yy,xx1,yy1,a,aa,b,bb]=(x,y,x1,y1)
(this is I tryed and it doesnt work :-( )
I have a points in my code (predefined - x,y,x1,y1) and I want change this points for a function (its mean write my own coordinate of points to the command window). Then I Interpolate and approximate this points by spline and polyfit.
Here is my code syntax (it works good, but I wanna make this like a function).. Thanks for any help, I just learning in Matlab so use simply answer :-)
CODE:
obr = imread('Pokus1.jpg');
obr = obr(:,:,1);
obr = im2double(obr);
figure(1)
imshow(obr,[]);
[a,b]=size(obr);
x=[19.25 ; 217.25 ; 523.25 ; 806.75 ; 1135.25 ; 1345.25 ; 1612.25];
y=[545.75 ; 364.25 ; 155.75 ; 92.75 ; 145.25 ; 256.25 ; 418.25];
x1=[163.25 ; 361.25 ; 778.25 ; 1007.75 ; 1175.75 ; 1409.75];
y1=[572.75 ; 358.25 ; 178.25 ; 200.75 ; 265.25 ; 425.75];
hold on
axis on
plot (x,y,'o');
xx = 1:0.01:b;
yy = spline(x,y,xx);
hold on
plot(x,y,'o',xx,yy, 'LineWidth', 3);
plot (x1,y1,'o');
xx1 = 1:0.01:b;
yy1 = spline (x1,y1,xx1);
hold on
plot(x1,y1,'o',xx1,yy1, 'LineWidth', 3);
hold off
figure(2)
imshow(obr,[]);
p = polyfit(x,y,2);
a = 1:0.01:b;
aa = polyval (p,a);
hold on
axis on
plot(x,y,'o',a,aa, 'LineWidth', 3);
p1 = polyfit(x1,y1,2);
b = 1:0.01:b;
bb = polyval (p1,b);
plot(x1,y1,'o',b,bb, 'LineWidth', 3);
hold off

2 个评论

format the code please: http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup
I did it :-) Could you help me please??

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 采纳的回答

The line
function [xx,yy,xx1,yy1,a,aa,b,bb]=(x,y,x1,y1)
needs to have the function name added between the "=" and the "("

更多回答(2 个)

First you need to give the function a name. Here I've called it my_function() and you should save it as my_function.m somewhere on the Matlab path.
function [xx,yy,xx1,yy1,a,aa,b,bb]=my_function(x,y,x1,y1)
-Eric

3 个评论

Yeah I did it :-( But it stil doesnt work..
I saved function [xx,yy,xx1,yy1,a,aa,b,bb]=my_function(x,y,x1,y1).
And when I want play function - from command window - for example :
[xx,yy,xx1,yy1,a,aa,b,bb]=my_function(19,545,163,572) i tell me:
??? Output argument "xx" (and maybe others) not assigned during call to "C:\Documents and Settings\blabla...
Do you know please how to write function syntax right??
That's still the function syntax. An output argument not assigned has to do with the code inside the function.
And could you help me how to fix it? When you look above on my code, how to make function? I would like to delete my own points (x,y,x1,y1) and use the function - write my own points..:-)

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I'm not entirely sure what you want this function to do. How about something like this? From the Matlab command prompt:
x=[19.25 ; 217.25 ; 523.25 ; 806.75 ; 1135.25 ; 1345.25 ; 1612.25];
y=[545.75 ; 364.25 ; 155.75 ; 92.75 ; 145.25 ; 256.25 ; 418.25];
x1=[163.25 ; 361.25 ; 778.25 ; 1007.75 ; 1175.75 ; 1409.75];
y1=[572.75 ; 358.25 ; 178.25 ; 200.75 ; 265.25 ; 425.75];
Then in my_function.m:
function [xx,yy,xx1,yy1,a,aa,b,bb]=my_function(x,y,x1,y1)
obr = imread('moon.tif');
obr = im2double(obr);
[a,b]=size(obr);
xx = 1:0.01:b;
yy = spline(x,y,xx);
xx1 = 1:0.01:b;
yy1 = spline (x1,y1,xx1);
p = polyfit(x,y,2);
a = 1:0.01:b;
aa = polyval (p,a);
p1 = polyfit(x1,y1,2);
b = 1:0.01:b;
bb = polyval (p1,b);
return
Then from the command prompt again:
[xx,yy,xx1,yy1,a,aa,b,bb]=my_function(x,y,x1,y1);
You might also want to pass the image in as a variable. Also, I've switched to moon.tif since I don't have your image.

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