Last night I wrote a short C LanguageProgram(In a Linux environment), compilation is successful, but a segment error is always reported during running. I was very depressed becauseCodeNot long. The main function has the following sentence:
Char * STR = "epmzm bpmzm QA eqtt bpmzm qa I EIG ";
The code in the future will operate on this string (the characters in the string are modified ). But changed
Char STR [] = "epmzm bpmzm QA eqtt bpmzm qa I
// MatlabA.cast
(); // double(A)A.cast
(); // single(A)A.cast
(); // int32(A)A.real(); // real(A)A.imag(); // imag(A)// if the original type equals destination type, no work is done
Eigen solves Linear Equations Ax = B
// Solve Ax = b. Result stored in x. Matlab: x = A \ b.x = A.ldlt().solve(b)); // A sym. p.s.d. #include
x = A.llt
variablesubexpr functions Sometimes the symbolic expressions returned by MATLAB are difficult to understand, and with the SUBEXPR function, you can simplify the expression by using a symbolic representation of the repeated occurrences of the sub-formula in the expression.C=sym (' C ', ' real ');X=sym (' x ', ' real ');S=solve (X^3-x+c)A=SUBEXPR (s) Get sigma = -108*c+12* ( -12+81*c^2) ^ (1/2)A =
[1/6*sigma^ (1/3) +2/sigma^ (1/3)][ -1/12*sigma^ (1/3) -1/sigma^ (1/3) +1/2*i*3^ (in) * (1/6*sigma^
input_data = rand (1000,3); % randomly generated 1000 samples, each with x, Y, z three properties Figure (1);% control the drawing window to 1Hold off;% so that the current axis and graphics no longer have the nature of being refreshed, close on this basis and then drawPLOT3 (Input_data (:, 1), Input_data (:, 2), Input_data (:, 3), ' Ro '); Percent Function PCA, Input_data, Out_dim % use this to switch methodsuse_svd_method=1;% changed to 0 after using the
EXERCISE:PCA and WhiteningNo. 0 Step: Data preparationUFLDL The downloaded file contains the dataset Images_raw, which is a 512*512*10 matrix, which is 10 images of 512*512(a) data-loadingUsing the Sampleimagesraw function, extract the numpatches image blocks from the Images_raw, each image block size is patchsize, and the extracted image blocks are stored in columns, respectively, in each column of the matrix patches, That is, patches (:, i) holds all the pixel values of the first image block(b
If you haven't done anything for a long time, nothing can be updated. As we started to do things in the past two days, problems are constantly emerging, and even the use of standard complex classes has problems. Let's talk about the problem first.
xxxx.cpp: In member function ‘void xxxx::xxxxxxxx()’:xxxx.cpp:100: error: ISO C++ forbids declaration of ‘type name’ with no typexxxx.cpp:100: error: expected primary-expression before ‘double’xxxx.cpp:100: error: expected ‘;’ before ‘double’make: ***
sample, rowvar is set to 0. CovMat is the covariance matrix.
(3) Calculate the feature value and Feature Matrix call the eig function in linalg of the linear algebra module in numpy. The feature value and feature vector can be obtained directly from covMat:
eigVals,eigVects=np.linalg.eig(np.mat(covMat))
EigVals stores feature values and row vectors. EigVects stores feature vectors. Each column carries a feature vector. Feature values correspond to f
by Eig function.The elements of the D diagonal are the eigenvalues (representing the scale of the scaling), and D is that each column of the q,v in the eigenvalue decomposition formula corresponds to the D column, representing the corresponding eigenvector, the σ in the eigenvalue decomposition.1. Decomposition MethodFeature decomposition of matricesso that a is a square of nxn , and there are n linearly independent eigenvectors。this way, a can
Grammar
[Y1,y2,...] = Feval (fhandle,x1,x2,..., xn)
[y1,y2,...] = feval (fname,x1,x2,..., xn)
Describe
The first use of Fhandle is a function of the handle,x1,x2,... xn is the function of the parameters, the function of handle how to write, look at the following exampleThe fname in the second usage is a string representation of the function name. Note that the name must be a simple name, it cannot contain a path, and it cannot contain an. m extension. X1,x2,... xn is an example of this functi
In the job need to find the eigenvalues and eigenvectors of a matrix, of course, the students will use the MATLAB built-in functions [V, D] = Eig (A), so that the diagonal matrix D is a small-to-large arrangement of the characteristics of the value. Some students want to be able to separate this diagonal element into a row vector or column vector, but also hope that the characteristics of the value from large to small arrangement, in order to achieve
laplas% of the normalized value is the K minimum eigenvalues and corresponding eigenvectors function [eig_val,special_vector] = Get_special_vector (laplas,k) Eig_con = Eig (Laplas); [Vector,x] = Eig (Laplas); [Sort_vec,index] = sort (Eig_con, ' descend '); eig_val = Eig_con (Index (1:K)); temp_vector = vector (:, index (1:K)); [Row,col] = size (temp_vector), y = zeros (Row,col), for i=1:row s = (sum (te
the symbol. Example 8. returns the transpose x = B 'x = 8 3 4 1 5 9 6 7 2 linear algebra of matrix B. in MATLAB, the Inverse Calculation of the matrix only requires the function "inv", which greatly simplifies the calculation process. Example 9. calculate the inverse x = inv (a) x = 3-3 1-3 5-21-2 1 of matrix A in MATLAB, and obtain the size of the determining factor of the matrix, it can be implemented using the "det" function. Example 10. Obtain the determinant x = det (a) x = 1 of matrix A.
operations can be implemented using the following code:The% stress vector is required for the line vector T = (t * n). '; % if n is a column vector T = n * t; % if n is the line vector%, the positive stress sigma = N. ' * T * n; % if n is the column vector sigma = n * T * n. '; % if n is the row vector% of the shear stress tau = sqrt (norm (t) ^2-sigma^2); The main stress and its corresponding direction [V, D] = Eig (t);It doesn't seem to
Capitalize each letter in S into lowercase, lowercase to uppercase, and other characters. The return value is the modified string-(NSString *) reversalupperandlowerforstring: (NSString *) s{Nsmutablestring *str=[[nsmutablestring Alloc]init];for (int i=0; iNSString *substr=[s Substringwithrange:nsmakerange (i, 1)];Unichar J=[substr characteratindex:0];if ((j>= ' a ') (j[Str appendString: [SubStr uppercasestring];}else if ((j>= ' A ') (j{[Str appendString: [SubStr lowercasestring];}Else{[Str APP
numerical solution is obtained that is close enough to the eigenvalues of the Matrix.Again, the computer can only solve the numerical solution and cannot find the analytic solution. def eig(self, A) : ifisNone : return forin range(020) : (Q, R) = self.qr_decomposition(A) A = self.multiply(R, Q) return AOn the diagonal is the eigenvalues of the Matrix.After finding the eigenvalues, according to
EIG function of MATLAB, the returned eigenvalues are a diagonal matrix with eigenvalues distributed diagonally, and the first I eigenvalues correspond to the eigenvectors of column IFifth step: Projecting the sample points onto the selected eigenvectorsAssuming that the sample column number is M, the characteristic number is n, minus the mean value after the sample matrix is Dataadjust (m*n), the covariance matrix is n*n, the K feature vector is sele
, r is the upper triangular Schur matrix, and the element on its main diagonal is the characteristic value of x.
[U,r]=schur (X) (5) The Hessenberg decomposition of arbitrary square matrices can be decomposed into x=php ', where p is unitary matrix, and the elements under the first diagonal of H are 0, i.e. H is the Hessenberg matrix.
[P,h]=hess (X) (6) The eigenvalue decomposition of arbitrary matrices evd any one n-order matrix X can be decomposed into XV=VD, where D is the eigenvalues o
use the command to modify the K valueR1/2/3/4 (config-if) #router Eig 90R1/2/3/4 (config-router) #metric weight 0 0 0 1 0 0Default metric Calculation formula: metric= [10^7/bandwidth (min) + delay (sum)/10] * 256See 3.3.3.3 's routing table on R1D 3.3.3.0 [90/665600] via 14.1.1.4, 00:00:58, FASTETHERNET0/1[90/665600] via 12.1.1.2, 00:00:58, fastethernet0/0Let's figure out how the next 665600 came from.Show Inter f0/0 s1/0 lo0We can see the delay of e
matrix on each base. The larger the eigenvalues, the greater the variance of the matrix on the corresponding eigenvector, the greater the power and the more information. However, eigenvalue decomposition also has a lot of limitations, such as the transformation of the matrix must be a square.In machine learning feature extraction, the meaning is that the maximum eigenvalue corresponding to the direction of the eigenvector contains the most information, if a certain number of characteristics are
The Method for Finding feature values and feature vectors sets a as a matrix of n-order. If the formula is true for the number "" and n-dimensional column vector X, it is called the feature value of matrix, A non-zero vector X is a feature vector corresponding to the feature value. For details, see section 1.3.5 and 1.3.6 feature value decomposition. For example, 1-89 calculate the matrix feature value and feature vector solution:> A = [-2 1 1; 0 2 0;-4 1 3];> [V, d] =
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