Re:

[address@hidden]

--- camilleri.jon
> Is this correct?
> 
> GNU Octave, version 4.0.0
> Copyright (C) 2015 John W. Eaton and others.
> This is free software; see the source code for copying conditions.
> There is ABSOLUTELY NO WARRANTY; not even for MERCHANTABILITY or
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> 
> Octave was configured for "i686-w64-mingw32".
> 
> Additional information about Octave is available at http://www.octave.org.
> 
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> Read http://www.octave.org/bugs.html to learn how to submit bug reports.
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> 
> >> sin(90);
> >> ans
> ans =  0.89400
> >> sin(-90)
> ans = -0.89400
> >>
> 
> -- 
> Jonathan Camilleri
> 
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> E-mail: address@hidden
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> 
Perhaps what you want to do is 

>> sin(pi/2);
or
>> sin(-pi/2);

Tatsuro