Math.h log10 function bug? [not a bug finally]

Development Libraries
2

I'm pretty sure it's a bug in printDouble function (at least in the version I used).

I've simulated it in python

import sys

val = float(sys.argv[1]);
precision = int(sys.argv[2])

sys.stdout.write(str(int(val)))
sys.stdout.write('.')

if val>0:
	frac = (val-int(val))*precision
else:
	frac = (int(val)-val)*precision
	
frac1 = frac
while (frac1/10!=0):
	frac1 = frac1/10
	if frac1!=0:
		precision=precision/10

while (precision/10!=0):
	precision = precision/10
	sys.stdout.write('0')
	
sys.stdout.write(str(int(frac))+'\n')

If I write python buggyprintDouble.py 1.057 1000 it says 1.56,
but 1.157 1000 says 1.157

My first try to fix it,

import sys

val = float(sys.argv[1]);
precision = int(sys.argv[2])

sys.stdout.write(str(int(val)))
sys.stdout.write('.')

if val>0:
	frac = (val-int(val))*precision
else:
	frac = (int(val)-val)*precision

lfact = 10
while int(lfact*(val-int(val)))==0 and lfact<precision:
	lfact*=10
	sys.stdout.write('0')
	
frac1 = frac
while (frac1/10!=0):
	frac1 = frac1/10
	if frac1!=0:
		precision=precision/10
	
sys.stdout.write(str(int(frac))+'\n')

That's, commet the while(precision/10!=0) bucle and add before a custom lfact correction (just for printing the left zeros).

Now python newprintDouble 1.057 1000 says 1.056 and python newprintDouble 1.157 1000 says 1.057.

Lets traslate it to C++ 8)