Please type the dimension of the matrix: n= important: 3 <= n <= 1000 !
How many eigenvalues should be found? numew= important: 1 <= numew <= min{n,300}
Give a limit for the number of steps : numsteps = important: numew <= numstep <= 300
choose the type of reorthogonalization:
choose epsaccept for Parlett's acceptance criterion epsaccept = important: 1.0e-16 <= epsaccept <= 1.0e-2
type your initial vector: n values are required. Values separated by comma or white space. Input can extend over several lines. If you want the vector generated internally at random, then type "xxx" here.
write here the piece of code which performs y=A*x. The result must be a vector y. Input is the vector x and n is the dimension. You might use: a (full) matrix A,(i.e. you address it as A(i,j), i,j=1,..,n which you must initialize here then , a temporary storage vector zeisum with n components, integer variables i,j,k (for loops e.g.), logical variables bool1, bool2, bool3, constants pi, e=exp(1), sqrt2=sqrt(2.0) . It is impossible to define new variables yourself.
c quindiagonal matrix with exact eigenvalues c 16sin(i*pi/(2(n+1)))**4, i=1,...,n y(1)=5.d0*x(1)-4.d0*x(2)+x(3) y(2)=-4.d0*x(1)+6.d0*x(2)-4.d0*x(3)+x(4) y(n-1)=-4.d0*x(n)+6.d0*x(n-1)-4.d0*x(n-2)+x(n-3) y(n)=5.d0*x(n)-4.d0*x(n-1)+x(n-2) do i=3,n-2 y(i)=6.d0*x(i)-(x(i-1)+x(i+1))*4.d0+x(i-2)+x(i+2) enddo
Click on "evaluate", in order to submit your input.
14.01.2013