Array operations in Matlab????? Is it possible to apply operations to the rows of a matrix as an array? Such as I have a matix A which is 30 rows by 1 column and I want to treat each row as a vector such that I can solve for the polynomial roots of each row using the roots comand (treating each row as its own equation and the matrix A a system of eqautions)? Also would it be possible to take the square roots of each row of a same size matrix. Meaning say I had the same size matrix and I want to take the square root of each row and have the output be a matrix of the same size just with the values of those square roots?
Hi, Iamfaster Welcome to PF! If you need to perform a function on each row of a matrix like function(A), where A is a 30x1 vector, I think you'll have to break it up and write a for loop Code (Text): for i=[1:length(A)] function(A(i)); end or if A is 30x2 (or more) Code (Text): for i=[1:length(A)] function(A(i,:)); end if you want to take the square root, you can find it using the .^ operator, which raises each element to a power as opposed to the ^ which performs matrix multiplication Code (Text): A.^(1/2)
Thanks, I am getting closer now but I still cant seem to enter the code in the right form. Say I have a matrix g1= 5 9 8 4 7 6 1 2 8 and I want a matrix g2= roots of each row as if each row was a vector consisting of the coeficients of a polynomial. I have tried using code such as for i=[1:length(g1)] g2(i)=roots(g1(i)); end but I keep getting errors. What am I doing wrong? What code would yield the results I desrire?
You're not indexing the entire row. g1(1) doesn't have any meaning for a m by n matrix when n>1. If you want to reference a single term, you need to put in the entire address lke so: g1(1,2) to reference the first row, second column. If you want to reference the entire row, you need to put in the : operator like so: g1(1,:) Just using : by itself is "shorthand" for explicitly defining the starting and ending conditions. If your matrix g is 4x4 Code (Text): g=[1,2,3,4 6,7,8,9 10,11,12,13 14,15,16,17] typing a=g(2,2:3) will give the result a=[7,8] b=g(:,1) will give the result b=[1;6;10;14] c=g(3,1:4) will give the result c=[10,11,12,13] and d=g(3,:) will give the same result as c. d=[10,11,12,13] Hope that helps,
yes it works because [1:5] evaluates to: 1, 2, 3, 4, 5 (you could say: for i = [1,4,18]) but you can tell the loop that you want "it" done for the numbers 1 through 5 instead of telling it that you want "it" done for the numbers 1, 2, 3, 4 and 5. (I guess you leave them in because of similarity with other programming languages that usually have brackets there, like in C/C++: for(i=1; i<5; i++) )