Hi!
On 2017-07-03, Fjordforsk A/S <fjordfors...@gmail.com> wrote:
> Hi, how does one write 10^(-8) ?
>
> Is it as the conventional way 10**(-8) or is it 10exp(-8) ?
Sage is based on Python, thus, 10**(-8) definitely works.
In addition, Sage uses a preparser to make the user interface still
a bit nicer than Python. Therefore, 10^(-8) works as well.
I don't know if you use Sage only by its user interface, or if
you also write programs. In the former case, my answer ends here.
In the latter case, I give you a bit more background, that may help
to avoid some pitfalls in programming:
In the user interface, You can also write
f(t) = sin(t^2)
and Sage's preparser will translate it into a sequence of commands that
defines t as a symbolic variable and f as a symbolic function
Here is what the preparser does internally:
sage: preparse('f(t) = sin(t^2)')
'__tmp__=var("t"); f = symbolic_expression(sin(t**Integer(2))).function(t)'
If you write a .py or .pyx module, the preparser would not be invoked,
und thus you have to write 10**(-8), whereas 10^(-8) would be interpreted
as bit-wise XOR.
And since var('t') inserts the new variable t into the global namespace,
to define the function f(t)=sin(t^2), you have to write something like
t = var('t')
f = symbolic_expression(sin(t**2)).function(t)
in your code.
Here, "2" would result in a Python integer, which is not the same
as a Sage Integer. Hence, if it is important for you to use the Sage
types rather than the Python types, you have to replace 2 by Integer(2)
or ZZ(2). And of course, you have to import these things first.
Best regards,
Simon
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