B <ÓFd%*ã@s\dZddlmZmZmZdgZddlmZddlm Z Gdd„de ƒZedkrXe eƒƒdS) z Machine arithmetics - determine the parameters of the floating-point arithmetic system Author: Pearu Peterson, September 2003 é)ÚdivisionÚabsolute_importÚprint_functionÚMachAr)Úany)Úerrstatec@s8eZdZdZeeedd„dfdd„Zdd„Zd d „ZdS)rañ Diagnosing machine parameters. Attributes ---------- ibeta : int Radix in which numbers are represented. it : int Number of base-`ibeta` digits in the floating point mantissa M. machep : int Exponent of the smallest (most negative) power of `ibeta` that, added to 1.0, gives something different from 1.0 eps : float Floating-point number ``beta**machep`` (floating point precision) negep : int Exponent of the smallest power of `ibeta` that, subtracted from 1.0, gives something different from 1.0. epsneg : float Floating-point number ``beta**negep``. iexp : int Number of bits in the exponent (including its sign and bias). minexp : int Smallest (most negative) power of `ibeta` consistent with there being no leading zeros in the mantissa. xmin : float Floating point number ``beta**minexp`` (the smallest [in magnitude] usable floating value). maxexp : int Smallest (positive) power of `ibeta` that causes overflow. xmax : float ``(1-epsneg) * beta**maxexp`` (the largest [in magnitude] usable floating value). irnd : int In ``range(6)``, information on what kind of rounding is done in addition, and on how underflow is handled. ngrd : int Number of 'guard digits' used when truncating the product of two mantissas to fit the representation. epsilon : float Same as `eps`. tiny : float Same as `xmin`. huge : float Same as `xmax`. precision : float ``- int(-log10(eps))`` resolution : float ``- 10**(-precision)`` Parameters ---------- float_conv : function, optional Function that converts an integer or integer array to a float or float array. Default is `float`. int_conv : function, optional Function that converts a float or float array to an integer or integer array. Default is `int`. float_to_float : function, optional Function that converts a float array to float. Default is `float`. Note that this does not seem to do anything useful in the current implementation. float_to_str : function, optional Function that converts a single float to a string. Default is ``lambda v:'%24.16e' %v``. title : str, optional Title that is printed in the string representation of `MachAr`. See Also -------- finfo : Machine limits for floating point types. iinfo : Machine limits for integer types. References ---------- .. [1] Press, Teukolsky, Vetterling and Flannery, "Numerical Recipes in C++," 2nd ed, Cambridge University Press, 2002, p. 31. cCsd|S)Nz%24.16e©)ÚvrrúD/opt/alt/python37/lib64/python3.7/site-packages/numpy/core/machar.pyÚdózMachAr.zPython floating point numberc Cs,tdd| |||||¡WdQRXdS)a! float_conv - convert integer to float (array) int_conv - convert float (array) to integer float_to_float - convert float array to float float_to_str - convert array float to str title - description of used floating point numbers Úignore)ZunderN)rÚ_do_init)ÚselfÚ float_convÚint_convÚfloat_to_floatÚfloat_to_strÚtitlerrr Ú__init__bszMachAr.__init__c.CsÊd}d}|dƒ}||} ||} |}xLt|ƒD].}||}||} | |}t||| kƒr.Pq.Wt|||jfƒ‚|}xLt|ƒD].}||}||} || |ƒ}t|dkƒr€Pq€Wt|||jfƒ‚|}||ƒ}d}|}xTt|ƒD]6}|d}||}||} | |}t||| kƒrâPqâWt|||jfƒ‚|| }|}xPt|ƒD]2}||}||} | |}t||| kƒrDPqDWt|||jfƒ‚||} d}t| || kƒr®d}||}||} |dkrÞt| || kƒrÞd}|d}||}|}xt|ƒD]}||}qüW|}xht|ƒD]J}||} t| || kƒr %sé é)!ÚrangerÚRuntimeErrorZdtypeÚlocalsÚabsÚibetaÚitÚnegepÚepsnegZ_str_epsnegÚmachepÚepsZ_str_epsÚngrdÚiexpÚminexpÚxminZ _str_xminÚmaxexpÚxmaxZ _str_xmaxÚirndrÚepsilonZtinyZhugeÚmathÚintZlog10Z precisionÚ resolutionZ_str_resolution).rrrrrrZ max_iterNÚmsgZoneZtwoZzeroÚaÚ_ZtempZtemp1ÚbZitempr Zbetar!Zbetahr,Ztempar"ZbetainÚir#r$r%r&ÚkÚzÚtZnxresÚyr'ZmxZizr)r(r*r+Újr.Ztenr0rrr rts\ $ $ zMachAr._do_initcCsd}||jS)NaòMachine parameters for %(title)s --------------------------------------------------------------------- ibeta=%(ibeta)s it=%(it)s iexp=%(iexp)s ngrd=%(ngrd)s irnd=%(irnd)s machep=%(machep)s eps=%(_str_eps)s (beta**machep == epsilon) negep =%(negep)s epsneg=%(_str_epsneg)s (beta**epsneg) minexp=%(minexp)s xmin=%(_str_xmin)s (beta**minexp == tiny) maxexp=%(maxexp)s xmax=%(_str_xmax)s ((1-epsneg)*beta**maxexp == huge) --------------------------------------------------------------------- )Ú__dict__)rZfmtrrr Ú__str__Gs zMachAr.__str__N) Ú__name__Ú __module__Ú__qualname__Ú__doc__Úfloatr/rrr<rrrr rsOTÚ__main__N)r@Z __future__rrrÚ__all__Znumpy.core.fromnumericrZnumpy.core.numericrÚobjectrr=Úprintrrrr ÚsF