dp2hx_c |

Table of contents## Proceduredp2hx_c ( D.p. number to hexadecimal string ) void dp2hx_c ( SpiceDouble number, SpiceInt hxslen, SpiceChar hxstr [], SpiceInt * hxssiz ) ## AbstractConvert a double precision number to an equivalent character string using a base 16 "scientific notation." ## Required_ReadingNone. ## KeywordsALPHANUMERIC CONVERSION ## Brief_I/OVARIABLE I/O DESCRIPTION -------- --- -------------------------------------------------- STRLEN P Max number of characters allowed in output string. number I D.p. number to be converted. hxslen I Available space for output string `hxstr'. hxstr O Equivalent character string, left justified. hxssiz O Length of the character string produced. ## Detailed_Inputnumber is the double precision number to be converted to a character string representation. hxslen is the maximum length of the output `hxstr'. The value defined by `hxslen' should be one plus the value large enough to hold any possible output. ## Detailed_Outputhxstr is the character string produced by this routine that 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" 0.0e0 "8" 8.0e0 "1" 1.0e0 "9" 9.0e0 "2" 2.0e0 "A" 10.0e0 "3" 3.0e0 "B" 11.0e0 "4" 4.0e0 "C" 12.0e0 "5" 5.0e0 "D" 13.0e0 "6" 6.0e0 "E" 14.0e0 "7" 7.0e0 "F" 15.0e0 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 bits bits bits length ---- -------- -------- ---------------------- 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 the 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. The character string produced will be blank padded on the right if hxssiz < hxslen. hxssiz is the length of the base 16 "scientific notation" character string produced by this routine. ## ParametersSTRLEN is the maximum number of characters permitted in the output string, excluding the null terminator character. The value of STRLEN is 255. ## Exceptions1) If the output character string is not long enough to contain the entire character string that was produced, the string will be truncated on the right. 2) If hxslen > hxssiz, the output character string will be blank padded on the right. 3) If the `hxstr' output string pointer is null, the error SPICE(NULLPOINTER) is signaled. 4) If the `hxstr' output string has length less than two characters, the error SPICE(STRINGTOOSHORT) is signaled, since the output string is too short to contain one character of output data plus a null terminator. ## FilesNone. ## ParticularsThis 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: ## ExamplesThe numerical results shown for this example may differ across platforms. The results depend on the SPICE kernels used as input, the compiler and supporting libraries, and the machine specific arithmetic implementation. 1) Convert a set of double precision numbers to their equivalent character string using a base 16 "scientific notation." Example code begins here. /. Program dp2hx_ex1 ./ #include <stdio.h> #include "SpiceUsr.h" int main() { /. Local constants. ./ #define HXSLEN 40 /. Local variables. ./ SpiceChar strval [HXSLEN]; SpiceInt i; SpiceInt len; /. Assign an array of double precision numbers. ./ SpiceDouble number[] = { 2.0e-9, 1.0, -1.0, 1024.0, -1024.0, 521707.0, 27.0, 0.0 }; /. Loop over the `number' array, call ## Restrictions1) The maximum number of characters permitted in the output string is specified by the parameter STRLEN. ## Literature_ReferencesNone. ## Author_and_InstitutionJ. Diaz del Rio (ODC Space) E.D. Wright (JPL) ## Version-CSPICE Version 1.1.0, 09-JUL-2021 (JDR) Changed the argument names "lenout", "string" and "length" to "hxslen", "hxstr" and "hxssiz" for consistency with other routines. Updated wrapper code to remove unnecessary chkin_c/chkout_c calls. Modified error tracing strategy in the "CHKOSTR" call to CHK_DISCOVER. Added the exceptions present in SPICELIB version and those derived from the use of "CHKOSTR". Edited the header to comply with NAIF standard. Added complete code example. -CSPICE Version 1.0.0, 10-APR-2010 (EDW) ## Index_Entriesconvert d.p. to signed normalized hexadecimal string convert d.p. number to encoded d.p. number convert d.p. to base 16 scientific notation |

Fri Dec 31 18:41:04 2021