This is right. The precision that you are asking for has no meaning. 
foreach (-2.0,-1.9,-1.5,-1.1,-1.0,-0.9,-0.5,-0.1,-0)
{
 printf("string=%5s digits=%9f, float2big=%24.16e\n", $_, $_, $_);
} 

__END__
prints:
string=   -2 digits=-2.000000, float2big=-2.0000000000000000e+000
string= -1.9 digits=-1.900000, float2big=-1.8999999999999999e+000
string= -1.5 digits=-1.500000, float2big=-1.5000000000000000e+000
string= -1.1 digits=-1.100000, float2big=-1.1000000000000001e+000
string=   -1 digits=-1.000000, float2big=-1.0000000000000000e+000
string= -0.9 digits=-0.900000, float2big=-9.0000000000000002e-001
string= -0.5 digits=-0.500000, float2big=-5.0000000000000000e-001
string= -0.1 digits=-0.100000, float2big=-1.0000000000000001e-001
string=    0 digits= 0.000000, float2big= 0.0000000000000000e+000

[download]
Update:Well Ooops..... Somehow there is a precision problem. Sorry I couldn't replicate it. 
foreach (-2.0,-1.9,-1.5,-1.1,-1.0,-0.9,-0.5,-0.1,-0)
{
 printf("string=%5s digits=%9f, float2big=%24.16e\n", $_, $_*0, $_*0);
} 

string=   -2 digits= 0.000000, float2big= 0.0000000000000000e+000
string= -1.9 digits= 0.000000, float2big= 0.0000000000000000e+000
string= -1.5 digits= 0.000000, float2big= 0.0000000000000000e+000
string= -1.1 digits= 0.000000, float2big= 0.0000000000000000e+000
string=   -1 digits= 0.000000, float2big= 0.0000000000000000e+000
string= -0.9 digits= 0.000000, float2big= 0.0000000000000000e+000
string= -0.5 digits= 0.000000, float2big= 0.0000000000000000e+000
string= -0.1 digits= 0.000000, float2big= 0.0000000000000000e+000
string=    0 digits= 0.000000, float2big= 0.0000000000000000e+000

[download]

In reply to Re^2: Negative zero from a multiplication by a zero? by Marshall
in thread Negative zero from a multiplication by a zero? by Anonymous Monk

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