Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>For a small 4x4 matrix, I would avoid dynamically allocating memory on the heap ... a simple one-dimensional array that you can index as a 2D array should suffice (i.e., the ordered pair (x,y) value would be <code>matrix_array[COLUMNS * y + x]</code>), especially considering that loading any single value in the array will also cause adjacent values to be stored on the processor's cache-line, speeding up access to any adjacent elements. The cache-loading can happen with heap-allocated memory as well, but the main reason to avoid heap allocation if possible for small matricies is that many sequential math operations will require you to return a temporary, and without r-value references, you're going to end up doing a lot of calls to <code>new</code> and <code>delete</code> inside the copy-constructors of those temporaries which will slow things down tremendously compared to quickly allocating memory on the stack.</p> <p>Secondly, I would suggest you go with a templated approach, as this will let your define you matrix for not only plain-old-data-types like <code>double</code>, etc., but also for any secondary composite types you may decide to define later, or import from another library such as rationals, complex numbers, etc. Whether you decide to add operator overloads is really up to you ... some people do not like it because it "hides" the complexity of what may be happening underneath the hood (i.e, <code>A * B</code> for <code>doubles</code> will be far simpler than <code>A * B</code> for a 4x4 <code>matrix&lt;double&gt;</code>). On the other-hand, it can greatly simplify the amount of code you write for complex math operations.</p>
    singulars
    1. This table or related slice is empty.
    1. POVector, Matrix, Algebra class Design
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USandand
    1. USJason
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COI know operator overloading can be abused ... but in this case it allows programming close to the problem domain. That's what the language feature was designed for, so IMHO this is an appropriate place to use it. And as @Jason noted, it will make coding complex operations *much* easier (and less error-prone).
      singulars
      1. PO
      1. USDavid
    2. COIn your opinion considering the we have move semantics and that a default matrix would take almost 0 memory, you would still not implement it with a pointer and allocate?
      singulars
      1. PO
      1. USmonamimani
    3. CO@user994652: Your matrices are extremely small (at most 16 cells for now). For small pieces of data like this, there's not really a reason to pay the price associated with heap allocations. Just stick with the stack for now, worry about the heap when things expand a bit more. Plus, move semantics only help when "copying" the data of a temporary value into another memory location. Most of the temporaries in math come from large expressions which are in the process of being evaluated, so most would not even benefit from move semantics.
      singulars
      1. PO
      1. USKen Wayne VanderLinde
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload