====== CollectScalars ======
----

====Description====
  * ''CollectScalars'' collects similar scalar factors in products.
====Examples====
----
Collect same scalars in product:
<sxh groovy;gutter:false>
println CollectScalars >> 'A_m*A^m*A_n*A^n'.t
</sxh>
<sxh plain; gutter:false>
   > (A_{m}*A^{m})**2
</sxh>

----
''CollectScalars'' may significantly simplify expression:
<sxh groovy;gutter:false>
println CollectScalars >> 't_mn*f^mn*t_ba*f^ba*R_ij + (t_mn*f^mn)**2*R_ij'.t</sxh>
<sxh plain; gutter:false>
   > 2*(t_{mn}*f^{mn})**2*R_{ij}
</sxh>


----
''CollectScalars'' takes into account symmetries of tensors:
<sxh groovy;gutter:false>
setSymmetric 't_mn'
println CollectScalars >> 't_mn*f^mn*t_ab*f^ba*R_ij'.t
</sxh>
<sxh plain; gutter:false>
   > (t_{mn}*f^{mn})**2*R_{ij}
</sxh>

----
''CollectScalars'' collects scalars with any complicated structure:
<sxh groovy;gutter:false>
println CollectScalars >> '(A_i + B_i)*(A^i + B^i)*(A_a + B_a)*(A^a + B^a)'.t
</sxh>
<sxh plain; gutter:false>
   > ((A^{a}+B^{a})*(A_{a}+B_{a}))**2
</sxh>

----

====See also====
  * Related guides: [[documentation:guide:applying_and_manipulating_transformations]], [[documentation:guide:list_of_transformations]]
  * JavaDocs: [[http://api.redberry.cc/redberry/1.1.9/java-api/cc/redberry/core/transformations/CollectScalarFactorsTransformation.html| CollectScalarFactorsTransformation]]
  * Source code: [[https://bitbucket.org/redberry/redberry/src/tip/core/src/main/java/cc/redberry/core/transformations/CollectScalarFactorsTransformation.java|CollectScalarFactorsTransformation.java]]