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Frequently Asked Questions

Why not use decimal C# data type ?

Decimal in C# is just not that good:

  • It is uses 12 bytes for mantissa (effectively 16)
  • It does not have CLR support. i.e. all operators will be working as functions (slower than DFP).TODO: Benchmark proof.

What is the Decimal64Utils.NULL?

In Java, all custom data types can only be represented by classes, which is very expensive. This approach requires a significant amount of memory and creates considerable pressure on the garbage collector. However, you can avoid this by working with decimal values packed into Java's long primitives.

Replacing the Decimal64 class with long values seems like a great idea until you encounter the problem of handling null references. How can null be represented using a long?

Decimal64 addresses this issue by introducing a special value: Decimal64Utils.NULL. According to the IEEE 754-2008 standard, NaN (Not a Number) values can be encoded in various ways. Decimal64Utils.NULL is one specific binary value from the possible NaN binary representations that was chosen as null value in DFP for Java.

Since this value is technically considered NaN according to the standard, the method Decimal64Utils.isNaN(Decimal64Utils.NULL) returns true. You should also keep this in mind if you intend to use the ValueTypeAgent.

Key points:

  • There is no null value defined in the IEEE 754-2008 standard.
  • Decimal64Utils.NULL is simply one specific binary representation of the possible NaN values.
  • The method Decimal64Utils.isNaN(Decimal64Utils.NULL) returns true.

What are the *Checked functions in Java?

The *Checked functions in Java are not intended to be used directly. These special functions are required just for ValueTypeAgent support.

How to quickly check a sign?

There are many is* functions in the DFP library for the fast sign check. The output values of these functions are presented in the next table.

Function -Infinity -1 0 1 Infinity NaN
isPositive false false false TRUE TRUE false
isNonNegative false false TRUE TRUE TRUE false
isNegative TRUE TRUE false false false false
isNonPositive TRUE TRUE TRUE false false false
isInfinity TRUE false false false TRUE false
isPositiveInfinity false false false false TRUE false
isNegativeInfinity TRUE false false false false false
isNaN false false false false false TRUE
isFinite false TRUE TRUE TRUE false false
isNonFinite TRUE false false false TRUE TRUE
isZero false false TRUE false false false
isNonZero TRUE TRUE false TRUE TRUE TRUE

Do we have a method of parsing value like "1.703E-5"?

All the parse() and tryParse() methods supports this scientific notation. Use the method you like best

Decimal64Utils.parse() or Decimal64Utils.tryParse()
Decimal64.parse() or Decimal64.tryParse()