Re: numerical values

[Rob Mahurin]

On Mar 20, 2008, at 9:47 AM, Przemek Klosowski wrote:
> As Ben pointed out, printf formats easily control the
> number of decimal places, as shown above. It is even
> possible to provide that number at runtime:
>
>   sprintf('%7.*f', 2, 123.4567)   -->    123.46
>   sprintf('%7.*f', 3, 123.4567)   -->    123.457
>
>
> Limiting the total number of decimal places is trickier: the printf
> formats don't seem to allow this control.

%g does this.

        octave:1> a = 123.456789             ---> a =  123.46
        octave:2> printf("%7g\n",a)                ---> 123.457
        octave:3> printf("%10g\n",a)               --->    123.457
        octave:4> printf("%10.2g\n",a)             --->    1.2e+02
        octave:5> printf("%10.3g\n",a)             --->        123
        octave:6> printf("%10.5g\n",a)             --->     123.46
        octave:7> printf("%10.7g\n",a)             --->   123.4568

You can cancel %g's zero-truncation with a %#g:

        octave:8> a = 123                    ---> a =  123
        octave:9> printf("%10.7g\n",a)             --->        123
        octave:10> printf("%#10.7g\n",a)   --->   123.0000

This is the C behavior.

Cheers,
Rob

--
Rob Mahurin
Dept. of Physics & Astronomy
University of Tennessee         phone: 865 207 2594
Knoxville, TN 37996             email: address@hidden