# diagsparse

Creates a sparse matrix by writing the entries of a vector on the diagonal.

## Contents

- Syntax
- Description
- Example
- Input Argument
- Output Argument
- Code

## Syntax

    diagh = diagsparse(h)

## Description

`diagh = diagsparse(h)` creates a sparse matrix, `diagh`, by writing the entries of the vector `h` on the diagonal.

## Example

    h = [1 4 5];
    diagh = diagsparse(h);

Result: diagh =

    (1,1)        1
    (2,2)        4
    (3,3)        5

## Input Argument

- h : a vector

## Output Argument

- diagh : matrix (stored as sparse matrix)

## Code

    function diagh = diagsparse(h)

    % method 1: slow
    % tic; diag1 = diag(h); toc

    % method 2: fast
    %tic
    i = 1:length(h);
    diagh = sparse(i,i,h);
    %toc

    end