What is the inclusive range of float and double in Java

Question

What is the inclusive range of float and double in Java   Why are you not recommended to use float or double for anything where precision is critical

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Java s Double class has members containing the Min and Max value for the type       2 -1074  lt   x  lt    2-2 -52   2 1023    where x is the double    Check out the Min VALUE and MAX VALUE static final members of Double    some People will suggest against using floating point types for things where accuracy and precision are critical because rounding errors can throw off calculations by measurable  small  amounts

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From Primitives Data Types         float  The float data type is a single-precision 32-bit IEEE 754   floating point  Its range of values is   beyond the scope of this discussion    but is specified in section 4 2 3   of the Java Language Specification  As   with the recommendations for byte   and short  use a float  instead of   double  if you need to save memory   in large arrays of floating point   numbers  This data type should never   be used for precise values  such as   currency  For that  you will need to   use the java math BigDecimal   class instead  Numbers and   Strings covers BigDecimal and   other useful classes provided by the   Java platform    double  The double data type is a double-precision 64-bit IEEE 754   floating point  Its range of values is   beyond the scope of this discussion    but is specified in section 4 2 3   of the Java Language Specification    For decimal values  this data type is   generally the default choice  As   mentioned above  this data type should   never be used for precise values  such   as currency       For the range of values  see the section 4 2 3 Floating-Point Types  Formats  and Values of the JLS

User · Answer

Of course you can use floats or doubles for  critical  things     Many applications do nothing but crunch numbers using these datatypes   You might have misunderstood some of the various caveats regarding floating-point numbers  such as the recommendation to never compare for exact equality  and so on

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Java s Primitive Data Types  boolean  1-bit  May take on the values true and false only   byte  1 signed byte  two s complement   Covers values from -128 to 127   short  2 bytes  signed  two s complement   -32 768 to 32 767  int  4 bytes  signed  two s complement   -2 147 483 648 to 2 147 483 647    long  8 bytes signed  two s complement   Ranges from -9 223 372 036 854 775 808 to  9 223 372 036 854 775 807   float  4 bytes  IEEE 754  Covers a range from 1 40129846432481707e-45 to 3 40282346638528860e 38  positive or negative    double  8 bytes IEEE 754  Covers a range from 4 94065645841246544e-324d to 1 79769313486231570e 308d  positive or negative    char  2 bytes  unsigned  Unicode  0 to 65 535

User · Answer

Binary floating-point numbers have interesting precision characteristics  since the value is stored as a binary integer raised to a binary power   When dealing with sub-integer values  that is  values between 0 and 1   negative powers of two  round off  very differently than negative powers of ten   For example  the number 0 1 can be represented by 1 x 10-1  but there is no combination of base-2 exponent and mantissa that can precisely represent 0 1 -- the closest you get is 0 10000000000000001   So if you have an application where you are working with values like 0 1 or 0 01 a great deal  but where small  less than 0 000000000000001   errors cannot be tolerated  then binary floating-point numbers are not for you   Conversely  if powers of ten are not  special  to your application  powers of ten are important in currency calculations  but not in  say  most applications of physics   then you are actually better off using binary floating-point  since it s usually at least an order of magnitude faster  and it is much more memory efficient   The article from the Python documentation on floating point issues and limitations does an excellent job of explaining this issue in an easy to understand form   Wikipedia also has a good article on floating point that explains the math behind the representation

[java] What is the inclusive range of float and double in Java?

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