Description:
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With sunfuncs (date_sunrise, date_sunset)

When I do date_sunset(time(), 46.49, -71.14, 90); (I forgot the output format). The server seems to be frozen and I can't load another page before I restart Apache...
Even with this line (with the output format) : echo date_sunset(time(), 1,  -71.14, 90, 90);


Next:
When asking for a String format, if the var "ret" is near 00:00 and adding a gmt negative (see sunfuncs.c), the output will be bad (-3:-3) (because of the gmt_offset).
because the line
sprintf(retstr, "%02d:%02d", N, (int) (60 * (ret - (double) N)));
doesn't care about negative or positive values
You should add
if(ret < 0){
    ret += 24;
}
(almost the same as #31853 but negative values appears on string and double)


In doc, it should explain a little more the decimal values for latitude, is it minutes (60 based) or 100 based.
Moreover, I spent time to realize that zenith was the angle for the sun when it is on the horizon (so almost always 90), it should be written in the doc.