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#include "filter_lowpass.h"
#include "complexdata.h"
#include <odinpara/ldrfilter.h>
void FilterLowPass::init(){
freq=0.0;
freq.set_unit("Hz").set_description("Cut-off frequency");
append_arg(freq,"freq");
}
bool FilterLowPass::process(Data<float,4>& data, Protocol& prot) const {
Log<Filter> odinlog(c_label(),"process");
Range all=Range::all();
TinyVector<int,4> shape=data.shape();
int nrep=shape(timeDim);
ComplexData<4> cdata(float2real(data));
cdata.partial_fft( TinyVector<bool,4>(true,false,false,false), true);
int centindex=nrep/2;
float maxfreq_Hz=1000.0*secureDivision(1.0, prot.seqpars.get_RepetitionTime());
int cutoffindex=int(secureDivision(freq, maxfreq_Hz)*centindex+0.5);
int plateauindex=int(0.8*cutoffindex+0.5);
ODINLOG(odinlog,normalDebug) << "plateauindex/cutoffindex=" << plateauindex << "/" << cutoffindex << STD_endl;
LDRfilter transition;
transition.set_function("Gauss");
for(int i=0; i<(centindex+1); i++) {
if(i>=plateauindex && i<=cutoffindex) {
float relpos=secureDivision(i-plateauindex, cutoffindex-plateauindex);
STD_complex factor(transition.calculate(relpos));
if((centindex-i)>=0) cdata(centindex-i, all, all, all)*=factor;
if((centindex+i)<nrep) cdata(centindex+i, all, all, all)*=factor;
}
if(i>cutoffindex) {
if((centindex-i)>=0) cdata(centindex-i, all, all, all)=STD_complex(0.0);
if((centindex+i)<nrep) cdata(centindex+i, all, all, all)=STD_complex(0.0);
}
}
cdata.partial_fft( TinyVector<bool,4>(true,false,false,false), false);
data=creal(cdata);
return true;
}
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