Dear Monks,

Just an update on this thread. I ran the following testcase on a Debian system w/o hardware DFP. I then did a Perl one-liner, that I believe does the same thing. I needed some printf statements to help figure out what I was doing, so I left them in to help any one else. 

/* ------------------------------------------------------------------ 
    To compile:  gcc -o dfpal2 dfpal2.c -L . -lDFPAL
   ------------------------------------------------------------------ 
+*/

#include <stdio.h>
#include <stdlib.h>
#include "dfpal.h"

int main(int32_t argc, char **argv)
{
    int     i, count;
    char    mystring[100];
    char    sn1[100];
    char    sn2[100];
    int32_t init_err, init_os_err;
    char    *err_str = NULL;
    dfpalflag_t st;
    decimal128 n1, n2;                    /* Declare the decimal floin
+ting point numbers */

    printf("Start:\n");
    if (dfpalInit((void *)malloc(dfpalMemSize()))     /* start the lib
+rary */
                       != DFPAL_ERR_NO_ERROR) {
        fprintf(stderr,"DFPAL init error\n");
        printf("Error:\n");
        dfpalEnd(free);
        return (1);
    }
    n1 = dec128FromString(argv[1]);
    n2 = dec128FromString(argv[2]);            /* assign a value by co
+nverting the input string to a demical */
    count = 60000000;
    printf("Initialized: %s \t %s\n",dec128ToString(n1,sn1),dec128ToSt
+ring(n2,sn2) );
    printf("for loop:\n");
    for (i = 0; i < count; i++)
    {
//          printf("Step %d: %s \t %s\n",i,dec128ToString(n1,sn1),dec1
+28ToString(n2,sn2) );
        n1 = dec128Multiply(n1, n2);            /* do the maths */
    //    printf("Step %d: %d \t %d\n",i,i,i );
     }

    printf("Final amount=%s\n",dec128ToString(n1,mystring));    /* pri
+nt the results */

    dfpalEnd(free);                    /* end the library cleanly */
}

[download]
The results were better than I expected. YMMV. 
~/dfpal# time ./dfpal2 10. 1.000001
Start:
Initialized:   10        1.000001
for loop:
Final amount=1141973130130727445029596475.971760

real    0m10.722s
user    0m10.725s
sys     0m0.000s

~/dfpal# time perl -e '$n1=10;$n2=1.000001;for ($i=0;$i<60_000_000;$i+
++) { $n1=$n1*$n2;} print "Final amount=$n1\t$n2\n";'

Final amount=1.14197312449358e+27       1.000001

real    0m8.698s
user    0m8.701s
sys     0m0.000s

~/dfpal#

[download]
I had expected that the software only solution would be several times slower than the binary floating point hardware. Big Surprise!

Comments welcome!

Regards...Ed

"Well done is better than well said." - Benjamin Franklin

In reply to Re: Decimal Floating Point (DFP) and does Perl needs DFP? by flexvault
in thread Decimal Floating Point (DFP) and does Perl needs DFP? by flexvault

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.