'Unexpected output' error using SVDS with function handle

14 次查看（过去 30 天）
Jeremy Myers
Jeremy Myers 2018-10-10
编辑： Christine Tobler 2018-10-10
I need to pass a function handle, which performs a matrix-vector multiplication, to SVDS. I have
[U,S,V] = svds( @(x,tflag) denseSparseMatvec(X, 'notransp', B1, B2), [m n], k);
where the output of denseSparseMatvec is m x n and I want the k largest singular values. I get the error
Unexpected output of function handle with flag 'notransp'. The expected output is a column
vector of length 20 and of type double.
If, as a test, I simply do M = denseSparseMatvec(X, 'notransp', B1, B2) and then [U,S,V] = svds(M, k), everything works fine.
What's going on here?

请先登录，再回答此问题。

回答（1 个）

Christine Tobler
Christine Tobler 2018-10-10
编辑：Christine Tobler 2018-10-10
Maybe the problem is that you use both x and X in the definition of the anonymous function? A matrix X in your workspace would be used every time, while the vector x that SVDS passes in is ignored.
Also, the function handle passed to SVDS must compute M*x if the input tflag is 'notransp', and compute M'*x if it is 'transp'.

类别

在 Help Center 和 File Exchange 中查找有关 Eigenvalues 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by