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  • Simulink: Specifying trajectory

    - by stanigator
    I would like to use jtraj to specify a trajectory in a Simulink model. Below are what I attempted to retrieve in the command prompt: Q0 = [1 1 0]; Q1 = [1+0.5*cos(2*20) 1+0.5*sin(2*20) 0]; t = 0:0.1:20; [Q, Qd, Qdd] = jtraj(Q0, Q1, t); However, I don't know how to include such trajectory data in the Simulink model easily. Any comments? Thanks in advance.

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  • Simulink sim of rician channel ber process

    - by bob
    Hi, I'm learning simulink and I want to use the rician channle block from the communications blockset. I'm told I need to change the format format. Would anyone have some sample code where they used the rician channels in simulink to model a bit error rate process?

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  • Find location using only distance and bearing?

    - by pinnacler
    Triangulation works by checking your angle to three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and it's to my right at 90 degrees." Repeat 2 more times for different targets and angles. Trilateration works by checking your distance from three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and I'm 100 meters away from that." Repeat 2 more times for different targets and ranges. But both of those methods rely on knowing WHAT you're looking at. Say you're in a forest and you can't differentiate between trees, but you know where key trees are. These trees have been hand picked as "landmarks." You have a robot moving through that forest slowly. Do you know of any ways to determine location based solely off of angle and range, exploiting geometry between landmarks? Note, you will see other trees as well, so you won't know which trees are key trees. Ignore the fact that a target may be occluded. Our pre-algorithm takes care of that. 1) If this exists, what's it called? I can't find anything. 2) What do you think the odds are of having two identical location 'hits?' I imagine it's fairly rare. 3) If there are two identical location 'hits,' how can I determine my exact location after I move the robot next. (I assume the chances of having 2 occurrences of EXACT angles in a row, after I reposition the robot, would be statistically impossible, barring a forest growing in rows like corn). Would I just calculate the position again and hope for the best? Or would I somehow incorporate my previous position estimate into my next guess? If this exists, I'd like to read about it, and if not, develop it as a side project. I just don't have time to reinvent the wheel right now, nor have the time to implement this from scratch. So if it doesn't exist, I'll have to figure out another way to localize the robot since that's not the aim of this research, if it does, lets hope it's semi-easy.

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  • MATrix LABoratory interview questions?

    - by Shane
    I programmed in MATrix LABoratory for many years, but switched to using R exclusively in the past few years so I'm a little out of practice. I'm interviewing a candidate today who describes himself as an expert? What interview questions that I should be asking?

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  • Project Euler problem 214, How can i make it more efficient?

    - by Once
    I am becoming more and more addicted to the Project Euler problems. However since one week I am stuck with the #214. Here is a short version of the problem: PHI() is Euler's totient function, i.e. for any given integer n, PHI(n)=numbers of k<=n for which gcd(k,n)=1. We can iterate PHI() to create a chain. For example starting from 18: PHI(18)=6 = PHI(6)=2 = PHI(2)=1. So starting from 18 we get a chain of length 4 (18,6,2,1) The problem is to calculate the sum of all primes less than 40e6 which generate a chain of length 25. I built a function that calculates the chain length of any number and I tested it for small values: it works well and fast. sum of all primes<=20 which generate a chain of length 4: 12 sum of all primes<=1000 which generate a chain of length 10: 39383 Unfortunately my algorithm doesn't scale well. When I apply it to the problem, it takes several hours to calculate... so I stop it because the Project Euler problems must be solved in less than one minute. I thought that my prime detection function might be slow so I fed the program with a list of primes <40e6 to avoid the primality test... The code runs now a little bit faster, but there is still no way to get a solution in less than a few hours (and I don't want this). So is there any "magic trick" that I am missing here ? I really don't understand how to be more efficient on this one... I am not asking for the solution, because fighting with optimization is all the fun of Project Euler. However, any small hint that could put me on the right track would be welcome. Thanks !

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  • Removing an array dimension where the elements sum to zero

    - by James
    Hi, I am assigning a 3D array, which contains some information for a number of different loadcases. Each row in the array defines a particular loadcase (of which there are 3) and I would like to remove the loadcase (i.e. the row) if ALL the elements of the row (in 3D) are equal to zero. The code I have at the moment is: Array = zeros(3,5) % Initialise array Numloadcases = 3; Array(:,:,1) = [10 10 10 10 10; 0 0 0 0 0; 0 0 0 0 0;]; % Expand to a 3D array Array(:,:,2) = [10 10 10 10 10; 0 0 0 0 0; 0 0 0 0 0;]; Array(:,:,3) = [10 10 10 10 10; 0 0 0 0 0; 0 0 20 0 0;]; Array(:,:,4) = [10 10 10 10 10; 0 0 0 0 0; 0 0 20 0 0;]; % I.e. the second row should be removed. for i = 1:Numloadcases if sum(Array(i,:,:)) == 0; Array(i,:,:) = [] end end At the moment, the for loop I have to remove the rows causes an indexing error, as the size of the array changes in the loop. Can anyone see a work around for this? Thanks

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  • Uiimport does not save variable to base workspace

    - by Tim
    I tried using uiimport to load a file to the base workspace.....It worked first time....but after trying again after a while...I wasnt seeing the variable in the base work space. I used the default variable name which is given by 'uiimport". This was the command I used: uiimport(filename) And two variables where created by default..."data" and "textdata"(which is the header)....but now when i run it is no longer saved in the base workspace I do not want to assign a variable to the uiimport like so... K = uiimport(filename) assignin(base,'green',K) I do not want to do that because My dataset has a text header and the data itself, and doing this would assign both "textdata" and "data" to "green" variable How would I be able to get the dimensions of ONLY the "data" in green and how would I pass only "data"(which is in the green variable in the workspace.."rmbr"...the green variable holds both "data" and "textdata") to another function. I was able to do all this when the uiimport automatically saved the variables in the base workspace....but somehow now it doesn't. I would appreciate any help or tips on this matter

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  • filter that uses elements from two arrays at the same time

    - by Gacek
    Let's assume we have two arrays of the same size - A and B. Now, we need a filter that, for a given mask size, selects elements from A, but removes the central element of the mask, and inserts there corresponding element from B. So the 3x3 "pseudo mask" will look similar to this: A A A A B A A A A Doing something like this for averaging filter is quite simple. We can compute the mean value for elements from A without the central element, and then combine it with a proper proportion with elements from B: h = ones(3,3); h(2,2) =0; h = h/sum(h(:)); A_ave = filter2(h, A); C = (8/9) * A_ave + (1/9) * B; But how to do something similar for median filter (medfilt2 or even better for ordfilt2)

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  • SOM for Detection

    - by Tim
    I would like to know how I can use SOM for disease detection. Given a lung cancer dataset, how can SOM be applied for detection, there are certain terminologies like, sensitivity, specificity and accuracy percentages....are there ways to calculate all these with the SOM algorithm? I would appreciate answers from anyone who can shed more light on this

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  • How do I remove an array dimension where the elements sum to zero?

    - by James
    I am assigning a 3D array, which contains some information for a number of different loadcases. Each row in the array defines a particular loadcase (of which there are 3) and I would like to remove the loadcase (i.e. the row) if ALL the elements of the row (in 3D) are equal to zero. The code I have at the moment is: Array = zeros(3,5) %# Initialise array Numloadcases = 3; Array(:,:,1) = [10 10 10 10 10; 0 0 0 0 0; 0 0 0 0 0;]; %# Expand to a 3D array Array(:,:,2) = [10 10 10 10 10; 0 0 0 0 0; 0 0 0 0 0;]; Array(:,:,3) = [10 10 10 10 10; 0 0 0 0 0; 0 0 20 0 0;]; Array(:,:,4) = [10 10 10 10 10; 0 0 0 0 0; 0 0 20 0 0;]; %# And to remove the second row: for i = 1:Numloadcases if sum(Array(i,:,:)) == 0 Array(i,:,:) = []; end end At the moment, the for loop I have to remove the rows causes an indexing error, as the size of the array changes in the loop. Can anyone see a work around for this?

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  • Interpolating 1D Gaussian into 2D Gaussian

    - by Drazick
    Let's say I have a 1D Gaussian function. Its length is 600 for that matter. I want to Interpolate it into 2D Gaussian of the size 600 X 600. This is the code I wrote (OTFx is the Gaussian Function, OTF - 2d Interpolated Function): [x, y] = meshgrid([-300:299], [-300:299]); r = sqrt((x .^ 2) + (y .^ 2)); OTF = interp1([-300:299], OTFx, r(:), 'spline'); OTF = reshape(OTF, [600, 600]); The problem is I get Overshoot at the end: How can I prevent it? Is there better Interpolating algorithm for Monotonic Descending Functions?

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  • how to create a changing variable for fsolve

    - by Shun Miyamoto
    i want fsolve to calculate the output for different uc each time (increasing uc by 0.001 each time). each output from fsolve should be sent to a simulink model seperatly. so i set a loop to do so, but i believe that at the currenty constellation (if it will work)will just calculate 1000 different values? is there a way to send out the values seperately? if not, how can i create a parameter uc. that goes from 0 to say 1000? i tried uc=0:0.001:1000, but again, the demension doen't seem to fit. how do i create a function that takes the next element of a vector/matrix each time the function is called? uc=0; for i=0:1000 x0=[1,1,1]; y=x0(1); u=x0(2); yc=x0(3); options=optimset('Display','off'); x= fsolve(@myfun,x0,options,uc,d,spacing_amplitude,spacing_width); end best regards

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  • Converting convex hull to binary mask

    - by Jonas
    I want to generate a binary mask that has ones for all pixels inside and zeros for all pixels outside a volume. The volume is defined by the convex hull around a set of 3D coordinates (<100; some of the coordinates are inside the volume). I can get the convex hull using CONVHULLN, but how do I convert that into a binary mask? In case there is no good way to go via the convex hull, do you have any other idea how I could create the binary mask?

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  • Sort a matrix with another matrix

    - by Jacob
    Suppose I have a matrix A and I sort the rows of this matrix. How do I replicate the same ordering on a matrix B (same size of course)? E.g. A = rand(3,4); [val ind] = sort(A,2); B = rand(3,4); %// Reorder the elements of B according the reordering of A This is the best I've come up with m = size(A,1); B = B(bsxfun(@plus,(ind-1)*m,(1:m)')); Out of curiosity, any alternatives?

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  • using load instead of other I/O command

    - by Amadou
    How can I modify this program using load-ascii command to read (x,y)? n=0; sum_x = 0; sum_y = 0; sum_x2 = 0; sum_xy = 0; disp('This program performs a least-squares fit of an'); disp('input data set to a straight line. Enter the name'); disp('of the file containing the input (x,y) pairs: '); filename = input(' ','s'); [fid,msg] = fopen(filename,'rt'); if fid<0 disp(msg); else [in,count]=fscanf(fid, '%g %g',2); while ~feof(fid) x=in(1); y=in(2); n=n+1; sum_x=sum_x+x; sum_y=sum_y+y; sum_x2=sum_x2+x.^2; sum_xy=sum_xy+x*y; [in,count] = fscanf(fid, '%f',[1 2]); end fclose(fid); x_bar = sum_x / n; y_bar = sum_y / n; slope = (sum_xy - sum_x*y_bar) / (sum_x2 - sum_x*x_bar); y_int = y_bar - slope * x_bar; fprintf('Regression coefficients for the least-squares line:\n'); fprintf('Slope (m) =%12.3f\n',slope); fprintf('Intercept (b) =%12.3f\n',y_int); fprintf('No of points =%12d\n',n); end

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  • how to apply iddata into calculation?

    - by Sam
    I am trying to figure out how to combine the input and output data into the ARX model and then apply it into the BIC (Bayesian Information Criterion) formula. Below is the code that I am currently working on: for i=1:30; %% Set Model Order data=iddata(output,input,1); model = arx(data,[8 9 i]); yp = predict(model,data); ye = regress(data,yp{1,1}(1:4018,1)); M(i) = var(yp); BIC(i)=(N+i*(log(N)-1))/(N-i)*log(M(i)); end But it does not work. It keep on giving me an error something like below: "The syntax "Data{...}" is not supported. Use the "getexp" command to extract individual experiments from an IDDATA object." I did not understand what does that mean. Can someone explain it to me and where do I do wrong on my piece of code? Thanks in advance. Sam.

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  • Percentage of white pixel

    - by AZIRAR
    After performing processing I want to calculate the percentage of white pixels between this images after the change. I'm doing this: var = (int2str(nnz(Img2)) / int2str(nnz(Img1))) * 100; but it returns as result ] What's the problem ?

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  • A dynamic array of a class, inside another separate class?

    - by pinnacler
    I'm working on a robot localization simulator and I created a class called "landmark". The end result is going to be a robot that is always centered and always faces the top of the screen. As it turns, the birds eye view map will rotate around the robot. To accomplish this, I'm assuming I can rotate one class and have all elements inside rotate as well. So, the landmark class has properties x,y, label, and radius. This is suppose to simulate a tree location in a forest. To test everything, I need "forest data," and I wrote a script to generate 100 trees in a 100m x 100m area. The script automatically generates values within an acceptable range for x,y, radius. The generated data is stored in an object called tempForest and is 100x3. Ideally, I want to create a class called "landmarks" (plural) that has 100 landmark instances inside. How would I instantiate 100 instances of landmark in one instance of landmarks using that randomly generated data? Ideally, I'd just type treeBeacons = landmarks(); and it would randomly populate 100 (user definable, set in config file) instances with x, y, radius data. I'm not sure how to deal with a dynamic array of class "Landmark", inside another single class "landmarks." Any ideas?

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  • Averaging corrupted images to eliminate the noise

    - by Mertie Pertie
    Hi all As you can get it from the title, I want to average some .jpg images which are corrupted by zero-mean Gaussian additive. After searching over internet, I figured out to add image matrices and divide the sum by the # of matrices. However the resultant image is totally black. Normally when the number of image increases then the resultant image gets better. But When I use more images it gets darker. I am using 800x600 black and white images with .jpg ext Here is the script I used; image1 = imread ('PIC1.jpg'); image2 = imread ('PIC2.jpg'); image3 = imread ('PIC3.jpg'); image4 = imread ('PIC4.jpg'); sum = image1 + image2 + image3 + image4; av = sum / 4; imshow(av); Thanks in advance

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  • Matab - Trace contour line between two different points

    - by Graham
    Hi, I have a set of points represented as a 2 row by n column matrix. These points make up a connected boundary or edge. I require a function that traces this contour from a start point P1 and stop at an end point P2. It also needs to be able trace the contour in a clockwise or anti-clockwise direction. I was wondering if this can be achieved by using some of matlabs functions. I have tried to write my own function but this was riddled with bugs and I have also tried using bwtraceboundary and indexing however this has problematic results as the points within the matrix are not in the order that create the contour. Thank you in advance for any help. Btw, I have included a link to a plot of the set of points. It is half the outline of a hand. The function would ideally trace the contour from ether the red star to the green triangle. Returning the points in order of traversal.

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  • Using polyfit to predict where the object falls ?

    - by ZaZu
    Hi there, I have information of an object being thrown at a parabolic pattern. There are 30 images in total taken at specific intervals from the start position till the end. Now I have managed to extract the x,y coordinates of the object being thrown in all 30 images... I think that using polyfit (or maybe polyval ? ) may help me predict where the object will fall after the first 15 images ... I just want to know, how can polyfit be used with the 30 x,y coordinates I have ? ( I have a loop to extract each image from a mat file 1 row at a time until 30 .. and then plot that image .. so should I use polyfit in the same loop before/after the plot ??? Any ideas ?? Thanks !

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