Module (chicken flonum)
Because CHICKEN supports a full numeric tower, operations can sometimes incur a subtantial overhead to simply detect the type of numbers you're passing in. When you know you're definitely dealing only with flonums, you can choose to use flonum-specific operations to avoid this overhead.
This is purely a performance hack. You might want to consider adding type annotations instead, this often gives the same performance boost without having to rewrite all numeric operators in your code.
Arithmetic floating-point operations
- fp+ X Yprocedure
- fp- X Yprocedure
- fp* X Yprocedure
- fp/ X Yprocedure
- fpgcd X Yprocedure
- fpneg Xprocedure
- fpmin X Yprocedure
- fpmax X Yprocedure
- fp= X Yprocedure
- fp> X Yprocedure
- fp< X Yprocedure
- fp>= X Yprocedure
- fp<= X Yprocedure
- fpfloor Xprocedure
- fpceiling Xprocedure
- fptruncate Xprocedure
- fpround Xprocedure
- fpsin Xprocedure
- fpcos Xprocedure
- fptan Xprocedure
- fpasin Xprocedure
- fpacos Xprocedure
- fpatan Xprocedure
- fpatan2 X Yprocedure
- fplog Xprocedure
- fpexp Xprocedure
- fpexpt X Yprocedure
- fpsqrt Xprocedure
- fpabs Xprocedure
- fpinteger? Xprocedure
Arithmetic floating-point operations.
In safe mode, these procedures throw a type error when given non-float arguments. In unsafe mode, these procedures do not check their arguments. A non-flonum argument in unsafe mode can crash the application.
Note: fpround uses the rounding mode that your C library implements, which is usually different from R5RS.
Flonum limits
- maximum-flonumconstant
- minimum-flonumconstant
- flonum-radixconstant
- flonum-epsilonconstant
- flonum-precisionconstant
- flonum-decimal-precisionconstant
- flonum-maximum-exponentconstant
- flonum-minimum-exponentconstant
- flonum-maximum-decimal-exponentconstant
- flonum-minimum-decimal-exponentconstant
Platform-specific flonum limits.
- flonum-print-precision #!optional PRECISIONprocedure
Gets and sets the number of significant digits printed for a floating-point number. PRECISION must be a positive fixnum. Returns the setting that was previously in effect.
The default print precision is 15 on nearly all systems, and 7 on the rare system on which the double type is only single-precision.
Note: To ensure read/write invariance for all floating-point numbers, you must increase print precision from 15 to 17 (or from 7 to 9). For example:
> (define a (expt 2 -53)) > (define b (+ a (* 2 (expt 10 -32)))) > (eqv? a b) #f > (flonum-print-precision 15) > (cons a b) (1.11022302462516e-16 . 1.11022302462516e-16) ;; same printed representation > (flonum-print-precision 17) > (cons a b) (1.1102230246251565e-16 . 1.1102230246251568e-16) ;; differs in last place
On the downside, this will result in unnecessarily precise representations of many numbers:
> (flonum-print-precision 17) > 0.1 0.10000000000000001
The maximum number of decimal digits required to uniquely represent all floating-point numbers of a certain precision is given by the formula ceil(1+N*log10(2)), where N is the number of bits of precision; for double-precision, N=53.
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