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Article contents:[[tags: manual]] [[toc:]] == 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 [[Types|type annotations]] instead, this often gives the same performance boost without having to rewrite all numeric operators in your code. === Arithmetic floating-point operations <procedure>(fp+ X Y)</procedure> <procedure>(fp- X Y)</procedure> <procedure>(fp* X Y)</procedure> <procedure>(fp/ X Y)</procedure> <procedure>(fp*+ X Y Z)</procedure> <procedure>(fpgcd X Y)</procedure> <procedure>(fpneg X)</procedure> <procedure>(fpmin X Y)</procedure> <procedure>(fpmax X Y)</procedure> <procedure>(fp= X Y)</procedure> <procedure>(fp> X Y)</procedure> <procedure>(fp< X Y)</procedure> <procedure>(fp>= X Y)</procedure> <procedure>(fp<= X Y)</procedure> <procedure>(fpfloor X)</procedure> <procedure>(fpceiling X)</procedure> <procedure>(fptruncate X)</procedure> <procedure>(fpround X)</procedure> <procedure>(fpsin X)</procedure> <procedure>(fpcos X)</procedure> <procedure>(fptan X)</procedure> <procedure>(fpasin X)</procedure> <procedure>(fpacos X)</procedure> <procedure>(fpatan X)</procedure> <procedure>(fpatan2 X Y)</procedure> <procedure>(fpsinh X)</procedure> <procedure>(fpcosh X)</procedure> <procedure>(fptanh X)</procedure> <procedure>(fpasinh X)</procedure> <procedure>(fpacosh X)</procedure> <procedure>(fpatanh X)</procedure> <procedure>(fplog X)</procedure> <procedure>(fpexp X)</procedure> <procedure>(fpexpt X Y)</procedure> <procedure>(fpsqrt X)</procedure> <procedure>(fpabs X)</procedure> <procedure>(fpinteger? X)</procedure> 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. {{fp*+}} implements fused multiply-add {{(X * Y) + Z}}. Note: {{fpround}} uses the rounding mode that your C library implements, which is usually different from R5RS. == Flonum limits <constant>maximum-flonum</constant><br> <constant>minimum-flonum</constant><br> <constant>flonum-radix</constant><br> <constant>flonum-epsilon</constant><br> <constant>flonum-precision</constant><br> <constant>flonum-decimal-precision</constant><br> <constant>flonum-maximum-exponent</constant><br> <constant>flonum-minimum-exponent</constant><br> <constant>flonum-maximum-decimal-exponent</constant><br> <constant>flonum-minimum-decimal-exponent</constant><br> Platform-specific flonum limits. <procedure>(flonum-print-precision [PRECISION])</procedure> 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}}. --- Previous: [[Module (chicken fixnum)]] Next: [[Module (chicken foreign)]] Description of your changes:

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