Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>I see two options for you. If you are working in the financial services industry, there are probably standards that your code should comply with for precision and accuracy, so you'll just have to go along with that, regardless of memory cost. I understand that that business is generally well funded, so paying for more memory shouldn't be a problem. :)</p> <p>If this is for personal use, then for maximum precision I recommend you use integers and multiply all prices by a fixed factor before storage. For example, if you want things accurate to the penny (probably not good enough), multiply all prices by 100 so that your unit is effectively cents instead of dollars and go from there. If you want more precision, multiply by more. For example, to be accurate to the hundredth of a cent (a standard that I have heard is commonly applied), multiply prices by 10000 (100 * 100).</p> <p>Now with 32-bit integers, multiplying by 10000 leaves little room for large numbers of dollars. A practical 32-bit limit of 2 billion means that only prices as high as $20000 can be expressed: 2000000000 / 10000 = 20000. This gets worse if you multiply that 20000 by something, as there may be no room to hold the result. For this reason, I recommend using 64-bit integers (<code>long long</code>). Even if you multiply all prices by 10000, there is still plenty of headroom to hold large values, even across multiplications.</p> <p>The trick with fixed-point is that whenever you do a calculation you need to remember that each value is really an underlying value multiplied by a constant. Before you add or subtract, you need to multiply values with a smaller constant to match those with a bigger constant. After you multiply, you need to divide by something to get the result back to being multiplied by the desired constant. If you use a non-power of two as your constant, you'll have to do an integer divide, which is expensive, time-wise. Many people use powers of two as their constants, so they can shift instead of divide.</p> <p>If all this seems complicated, it is. I think the easiest option is to use doubles and buy more RAM if you need it. They have 53 bits of precision, which is roughly 9 quadrillion, or almost 16 decimal digits. Yes, you still might lose pennies when you are working with billions, but if you care about that, you're not being a billionaire the right way. :)</p>
    singulars
    1. This table or related slice is empty.
    1. POFixed Point Arithmetic in C Programming
      singulars
      1. PTQuestion
    1. PTAnswer
    1. This table or related slice is empty.
    1. USRandall Cook
    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. This table or related slice is empty.
 

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