Summary

A fixed place numeric library designed for performance.

All numbers have a fixed 7 decimal places, and the maximum permitted value is +- 99999999999, or just under 100 billion.

The library is safe for concurrent use. It has built-in support for binary and json marshalling.

It is ideally suited for high performance trading financial systems. All common math operations are completed with 0 allocs.

Design Goals

Primarily developed to improve performance in go-trader. Using Fixed rather than decimal.Decimal improves the performance by over 20%, and a lot less GC activity as well. You can review these changes under the 'fixed' branch.

If you review the go-trader code, you will quickly see that I use dot imports for the fixed and common packages. Since this is a "business/user" app and not systems code, this provides 2 major benefits: less verbose code, and I can easily change the implementation of Fixed without changing lots of LOC - just the import statement, and some of the wrapper methods in common.

The fixed.Fixed API uses NaN for reporting errors in the common case, since often code is chained like:

   result := someFixed.Mul(NewS("123.50"))

and this would be a huge pain with error handling. Since all operations involving a NaN result in a NaN, any errors quickly surface anyway.

Performance

BenchmarkAddFixed-2         	2000000000	         0.85 ns/op	       0 B/op	       0 allocs/op
BenchmarkAddDecimal-2       	 3000000	       472 ns/op	     400 B/op	      10 allocs/op
BenchmarkAddBigInt-2        	100000000	        18.8 ns/op	       0 B/op	       0 allocs/op
BenchmarkAddBigFloat-2      	20000000	       109 ns/op	      48 B/op	       1 allocs/op
BenchmarkMulFixed-2         	200000000	         6.14 ns/op	       0 B/op	       0 allocs/op
BenchmarkMulDecimal-2       	20000000	        96.0 ns/op	      80 B/op	       2 allocs/op
BenchmarkMulBigInt-2        	100000000	        22.2 ns/op	       0 B/op	       0 allocs/op
BenchmarkMulBigFloat-2      	30000000	        50.9 ns/op	       0 B/op	       0 allocs/op
BenchmarkDivFixed-2         	100000000	        19.8 ns/op	       0 B/op	       0 allocs/op
BenchmarkDivDecimal-2       	 1000000	      1206 ns/op	     928 B/op	      22 allocs/op
BenchmarkDivBigInt-2        	20000000	        67.6 ns/op	      48 B/op	       1 allocs/op
BenchmarkDivBigFloat-2      	10000000	       148 ns/op	      64 B/op	       2 allocs/op
BenchmarkCmpFixed-2         	2000000000	         0.28 ns/op	       0 B/op	       0 allocs/op
BenchmarkCmpDecimal-2       	100000000	        10.8 ns/op	       0 B/op	       0 allocs/op
BenchmarkCmpBigInt-2        	200000000	         8.10 ns/op	       0 B/op	       0 allocs/op
BenchmarkCmpBigFloat-2      	200000000	         8.39 ns/op	       0 B/op	       0 allocs/op
BenchmarkStringFixed-2      	20000000	        76.1 ns/op	      32 B/op	       1 allocs/op
BenchmarkStringNFixed-2     	20000000	        72.9 ns/op	      32 B/op	       1 allocs/op
BenchmarkStringDecimal-2    	 5000000	       328 ns/op	     144 B/op	       5 allocs/op
BenchmarkStringBigInt-2     	10000000	       212 ns/op	      80 B/op	       3 allocs/op
BenchmarkStringBigFloat-2   	 3000000	       568 ns/op	     272 B/op	       8 allocs/op
BenchmarkWriteTo-2          	20000000	        69.9 ns/op	      27 B/op	       0 allocs/op

The "decimal" above is the common shopspring decimal library

Compatibility with SQL drivers

By default Fixed implements decomposer.Decimal interface for database drivers that support it. To use sql.Scanner and driver.Valuer implementation flag sql_scanner must be specified on build.