In this case, the right side must contain the same number of elements as A. On the left side of an assignment statement, A(:) fills A, preserving its shape from before. Is all the elements of A, regarded as a single column. There is a function called 'spap2' which does exactly this, but I need to calculate the B-form without using it or any other built-in function which gives the B-form directly. The vector includes A(i,j,k,1), A(i,j,k,2), A(i,j,k,3), and so on. my task is to write a code to find out the B-form of the spline f given knots, degree of the polynomial, data sites x and data values y such that f(x(j)) y(j) for all j. Is the k th page of three-dimensional array A. The following table describes its use for this purpose (let us have a matrix A) − Format You can use the colon operator to create a vector of indices to select rows, columns or elements of arrays. the backslash operator) or a Moore-Penrose pseudo-inverse: x1 = A\b īut do remember that such a system does not have a unique solution, so both the pseudo-inverse and the backslash operator may (and in this case will) return very different solutions, whether any of them is acceptable really depends on your application.MATLAB executes the statement and returns the following result −Ġ 0.3927 0.7854 1.1781 1.5708 1.9635 2.3562 To solve your actual problem A*x=b for x, you can try to use mldivide (a.k.a. Interestingly enough when I plug in your matrix into matlab, I get the following for det(B): -1.7764e-015. Changing a few entries might make your matrix regular (non-singular), but it is not guaranteed to work and it will solve a different problem. B = [5 1 -2 0 0 -1 -1 0 0 īoth with VPA and floating points you will get that the rank is 8, the size is and the determinant is practically 0, i.e. If you want to use MATLAB to get a result that corresponds to a manual calculation, you can use the Symbolic Toolbox and its vpa (variable precision arithmetic) to work around possible numerical problems at the cost of a slower calculation. In addition, it will include the sum, mean, and standard deviation. The statistical analysis will find the total number of data points as well as the minimum, maximum, and range. The matrix equations will be in the form AxB. For a 9x9 matrix, this indeed means that the matrix is not invertible for doubles (as the rank function accounts for machine precision). This instruction set explains how to solve a matrix equation and perform statistical analysis on a matrix in MATLAB. You can see that this Matrix is not of full rank by executing the rank function: rank(A) = 8. Since you are working with floating point numbers, this sometimes causes other subtle problems, one of which you can see in the result of det(A), which is in the order of 1e-16, i.e. You could verify that manually (haven't taken the time to do so), but MATLAB already points this out by showing that warning. The matrix you provided isn't of full rank, so it isn't invertible. The problem is indeed in your mathematics.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |