Can't find the syntax errors

Question

Ted Ersek 2013-5-2

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/74358-can-t-find-the-syntax-errors

评论： Walter Roberson 2022-5-19

I am using MATLAB, SeduMi and YALMIP to implement the algorithm published here. I know I have SeDuMi and YALMIP installed correctly. Before implementing that complicated algorithm, I wanted to use the same approach on an easier problem. With that in mind I tried the code that below, but I get syntax errors. Please show me how to fix the errors. If you can get it working that's even better. The syntax errors are:

Keyword for is underlined red with the message: "Invalid use of keyword."
norm(residulas,Inf)); has the right most ')' underlined red with the message:"Parse error at ')': usage might be invalid MATLAB syntax."
Keyword end is underlined red with the message: "Parse error at END: usage might be invalid MATLAB syntax."

addpath(genpath('C:\Program Files\MATLAB\R2010b\toolbox\yalmip'))
path(path,'D:\Documents and Settings\My Documents\MATLAB\SeDuMi_1_1')
path(path, 'D:\Documents and Settings\My Documents\MATLAB\SeDuMi_1_1\convr')
xvals = 1:0.1:7;
yvals = -xvals.^2+8*xvals-15.5;
residuals = zeros(length(xvals));
% a, w, phi, c  are parameters to be optimized
a = sdpvar(1,1);
w = sdpvar(1,1);
phi  = sdpvar(1,1);
c = sdpvar(1,1);
delta_step = sdpvar(4,1);
options = sdpsettings('solver','sedumi','usex0',1,'verbose',1);
assign(a,-10.58);
assign(w,0.47);
assign(phi,1.2);
assign(c,-9.87);
% determine values of a, w, phi, c that give a minimax 
% approximation of (yvals, xvals) using   y = a*cos( w*x + phi) + c
% BTW:     It seems the solution is  y = -10.6072*cos(0.4729*x+1.25)-9.9049
constraints = [ -11<=a<=-9, 0.35<=w<=0.7, 0.8<=phi<=1.25, -11<=c<=-6,...
   norm(delta_step,2)<=0.04 ];
% 2nd argument of solvesdp is a for loop followed by norm(residuals,inf)
solvesdp(constraints,...
for k=1:length(xvals)
   xval=xvals(k);
   yval=yvals(k);
   % gradient of (a*cos( w*x + phi) + c) WRT (a,b,phi,c)
   gradient = [cos(w*xval)+phi,-a*xval*sin(w*xval)+phi,...
      -a*sin(w*xval)+phi,1];   
   step=gradient*(delta_step);
   residuals(k)=yval-(a*cos(w*xval+phi)-c)+step;
end
norm(residuals,Inf));
solution = [double(a),double(w),double(phi),double(c)];

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Walter Roberson 2022-5-18

在 MATLAB Online 中打开

im102 imresize(im101,[312 312])

That line would be interpreted as a request to call a function named im102 passing in a character vector 'imresize(im101,[312 312])'

FileName1 = uigetfile("*",");

That would create a scalar string object "*" for the first parameter. The second parameter would be a syntax error as double-quote by itself is not valid syntax in MATLAB. Perhaps you intended two single quotes in a row, '' instead of a single " . However, to be consistent with using a string scalar for the first parameter if the intention is to pass emptiness for the second parameter, it would be more readable to pass ""

K1=im102(:,:,.2);

That line is consistent with the possibility that im102 is a function. It is not consistent with the possibility that it is a variable, because using 0.2 as an index will not work.

showMatchedFeatures(im103,im203,matchedPoints1,matchedPoints2, montage','Parent',ax)

That line contains a call to the function named montage() with no arguments, and if that does not error out, it does a conjugate transpose of the return value. I have to wonder whether the intent was to instead use the character vector 'montage' with the leading single quote.

Johan Löfberg 2022-5-19

and there is no reason to assign initials, as sedumi does not support warmstarts (and even if it did, warmstarting primal-dual solvers with primals only will never help more than absolutely marginally)

Walter Roberson 2022-5-19

It looks as if optimize() was available at least as early as 2010, but that solvesdp was being worked on up to at least 2014.

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Answer 1

Alan Weiss 2013-5-2

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/74358-can-t-find-the-syntax-errors#answer_84228

编辑：Alan Weiss 2013-5-2

在 MATLAB Online 中打开

Thank you for the clarification. Take a look at these lines, towards the bottom of your code:

 solvesdp(constraints,...
 for k=1:length(xvals)

Obviously, there should be something in between these lines, to close the parentheses in the solvesdp function. After that, you can write a for loop and it should work correctly.

What I mean is, you need to write your for loop separately, outside the solvedsp function call. You might need to rework the function definition so that it expects the correct thing. Make a variable that is the result of the for loop or something, and pass that variable to the function.

Alan Weiss

MATLAB mathematical toolbox documentation

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Rahul Meshram 2022-5-17

clear all; FileName1 = uigetfile("*", "); im101 = imread(FileName1); im102 imresize(im101,[312 312]); K1=im102(:,:,.2); im103 = rgb2gray(im102); im103 = imbinarize(im103); imshow(im103);

FileName2 = uigetfile("** ,"); im201 = imread(FileName2); im202= imresize(im201,[312 312]); K2 =im202(:,:,2); im203 = rgb2gray(im202); im203= imbinarize(im203); imshow(im203);

P1 = detectSURFFeatures(im103); strongest = P1.selectStrongest(200); plot(strongest);

P2 = detectSURFFeatures(im203); [f1,valid_points1] = extractFeatures(im103,P1); [f2,valid_points2] = extractFeatures (im203,P2); indexPairs = matchFeatures(f1,f2);

disp(indexPairs); disp(length(indexPairs));

matchedPoints1 = valid_points 1 (indexPairs(:,1));

matchedPoints2 = valid_points2(indexPairs(:,2));

figure; ax = axes; showMatchedFeatures(im103,im203,matchedPoints1,matchedPoints2, montage','Parent',ax)

title('Counterfeit Currency Detection');

if length(indexPairs) >=80 msgbox('Currency Is Real");

else msgbox('Currency Is Counterfeit'); end

Here is one error occurred, this is syntax error. How can I solve for fake currency detection