# Performance TUning Options¶

You can safely let this options to theur default value.

The following documentation has been extracted automatically from the comments found in the source code. Discard Parameters. object variable.

class Parameters_module.Parameters

The input variables are read from the input file. The input file is written with python syntax. The Input file is interpreted as python after a preprocessing The preprocessing was introduced at the time of HST-> PYHST transition to maintaing compatibility with:

• NO/YES meaning 0/1

• items containing FILE in their name can be initialized without using the “” which are otherwise necessary for strings

The input file has to set (some of) the following variables. To setup easily an input file you are suggested to start from one of the examples given in the doc.

TRYEDFCONSTANTHEADER = 1

When enabled (default), PyHST assumes that all the projections have the same header size, if the first and the last do. This may lead to a slight gain of performance. If the projections do not have the same header size, then set this option to 0. If CURRENT_NAME is set, then TRYEDFCONSTANTHEADER is set to zero beacaus all projections need to be read.

TRYGPUCCDFILTER = 1

When GPU is available the CCD median filter for removing hot-spots will be done on GPU. This is the default option. However it may be interesting to set it to zero to check if (on CPU with many cores ) The CPU implementation is faster.