[Qgis-user] How to use 'Calculator' algorithm in modeler QGIS 2.1

[Yasser Said Lopez de Olmos Reyes]

Dear list,

I've been trying to use the "Calculator" algorithm from Modeler-only tools
in QGIS 2.1 modeler (or SEXTANTE modeler?) because I read in User Guide it
is a "simple arithmetic calculator that you can use to modify numerical
values". So, I need to modify inside a model some numerical values but the
only other help I have found inside this algorithm is "You can refer
numerical values in you formula, using             single-letter variables,
as follows:a->variable_name" (sic).

English is not my language so maybe there is something I couldn't catch
from this help. I tried to find an example inside the Example Models too,
but there are not use cases. Therefore, I'm hoping you can help me to
figure out how to use this "Calculator" algorithm to obtain the squared
value of a numerical entry and use the result in a r.mapcalculator
opertation.

Let us say some user enters a value of "5", how can I get "25.0" and then
use this 25 in a raster calculation (r.mapcalculator) formula (A/25.0)?

Thank you all for your always useful help.

---
Yasser Said López de Olmos Reyes

Laboratorio de Manejo de Recursos Naturales
Universidad Autónoma Metropolitana, Unidad Iztapalapa
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