cspice_dp2hx

 Abstract I/O Examples Particulars Required Reading Version Index_Entries
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#### Abstract

```
CSPICE_DP2HX converts a double precision number to an equivalent character
string using a base 16 ``scientific notation.''

For important details concerning this module's function, please refer to
the CSPICE routine dp2hx_c.

```

#### I/O

```
Given:

number   the scalar double precision number to convert to a character
string representation.

the call:

cspice_dp2hx, number, string

returns:

string   scalar string produced by this routine which represents
'number' in a base 16 ``scientific notation,'' e.g.:

672.0 = '2A^3' = ( 2/16 + 10/( 16**2 ) ) * 16**3

and

-11.0 = '-B^1' = - ( 11/16 ) * 16**1.

The following table describes the character set used to
represent the hexadecimal digits and their corresponding
values.

Character    Value         Character    Value
---------    ------        ---------    ------
'0'         0.0D0          '8'         8.0D0
'1'         1.0D0          '9'         9.0D0
'2'         2.0D0          'A'        10.0D0
'3'         3.0D0          'B'        11.0D0
'4'         4.0D0          'C'        12.0D0
'5'         5.0D0          'D'        13.0D0
'6'         6.0D0          'E'        14.0D0
'7'         7.0D0          'F'        15.0D0

The caret, or hat, character, '^', is used to
distinguish the exponent.

The plus sign, '+', and the minus sign, '-', are used,
and they have their usual meanings.

In order to obtain the entire character string produced
by this routine, the output character string should be
at least N characters long, where

# of bits per double precision mantissa + 3
N = 3 + ----------------------------------------------
4

# of bits per double precision exponent + 3
+ ---------------------------------------------- .
4

There should be one character position for the sign of
the mantissa, one for the sign of the exponent, one for
the exponentiation character, and one for each
hexadecimal digit that could be produced from a mantissa
and an exponent.

The following table contains minimum output string
lengths necessary to obtain the complete character
string produced by this routine for some typical
implementations of double precision numbers.

Double precision number
Size Mantissa Exponent    Minimum output string length
bits   bits     bits
---- -------- --------    ----------------------------
64   48       15          3 + 12 + 4 = 19
64   55+1     8           3 + 14 + 2 = 19 (VAX)
64   52       11          3 + 13 + 3 = 19 (IEEE)

The base 16 ``scientific notation'' character string
produced by this routine will be left justified and
consist of a contiguous sequence of characters with one
of following formats:

(1)   h h h h  ... h ^H H  ... H
1 2 3 4      n  1 2      m

(2)   -h h h h  ... h ^H H  ... H
1 2 3 4      n  1 2      m

(3)   h h h h  ... h ^-H H  ... H
1 2 3 4      n   1 2      m

(4)   -h h h h  ... h ^-H H  ... H
1 2 3 4      n   1 2      m

where

h   and  H   denote hexadecimal digits
i        j

'^'          denotes exponentiation ( base 16 )

and

'+' and '-'  have their usual interpretations.

```

#### Examples

```
Any numerical results shown for this example may differ between
platforms as the results depend on the SPICE kernels used as input
and the machine specific arithmetic implementation.

The following input and output argument values illustrate the
action of cspice_dp2hx for various input values of 'number'.

Note: The hat or caret, '^', signals an exponent.

number             string
-----------------  -----------------------------
2.0D-9         89705F4136B4A8^-7
1.0D0          1^1
-1.0D0         -1^1
1024.0D0          4^3
-1024.0D0         -4^3
521707.0D0          7F5EB^5
27.0D0          1B^2
0.0D0          0^0

```

#### Particulars

```
This routine converts a double precision number into an equivalent
character string using a base 16 ``scientific notation.'' This
representation allows the full precision of a number to be placed
in a format that is suitable for porting or archival storage.

This routine is one of a pair of routines which are used to
perform conversions between double precision numbers and
an equivalent base 16 ``scientific notation'' character string
representation:

cspice_dp2hx -- Convert a double precision number into a base 16
``scientific notation'' character string.

cspice_hx2dp -- Convert a base 16 ``scientific notation''
character string into a double precision number.

```

```
ICY.REQ

```

#### Version

```
-Icy Version 1.0.0, 29-APR-2009 (EDW)

```

#### Index_Entries

```
convert d.p. to signed normalized hexadecimal string
convert d.p. number to encoded d.p. number
convert d.p. to base 16 scientific notation

```
`Wed Apr  5 17:58:00 2017`