//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

//INITIAL CALCULATIONS

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

//INPUTS

//SUNPOS

$costetazs=$SUNPOS['costetazs'];

$cosfis=$SUNPOS['cosfis'];

$gammas=$SUNPOS['gammas'];

$tetazs=$SUNPOS['tetazs'];

$fis=$SUNPOS['fis'];

//HI

$G0=$HI['G0'];

$B0=$HI['B0'];

$D0=$HI['D0'];

//ANISO

$k1=$ANISO['k1'];

$k2=$ANISO['k2'];

//PVGEN

//Common

$NBGH=$PVGEN['NBGH'];

$NBGV=$PVGEN['NBGV'];

$NBT=$PVGEN['NBT'];

//This tracker

$Inclination_rack=$PVGEN['Track2VE']['Inclination_rack'];

$LEO=$PVGEN['Track2VE']['LEO'];

$LNS=$PVGEN['Track2VE']['LNS'];

$ALARG=$PVGEN['Track2VE']['ALARG'];

$RSEV=$PVGEN['Track2VE']['RSEV'];

$RSEH=$PVGEN['Track2VE']['RSEH'];

$LNS_rack=$PVGEN['Track2VE']['LNS_rack'];

$ALARGF=$PVGEN['Track2VE']['ALARGF'];

$NF=$PVGEN['Track2VE']['NF'];

$NBFV=$PVGEN['Track2VE']['NBFV'];

//OTHER PARAMETERS

//Degree of dust, model parameters

$DDP=DustDegreeParameters($OPTIONS['DustDegree']);

$ar=$DDP['ar'];

$c2=$DDP['c2'];

$Transm=$DDP['Transm'];

//Shading, model coefficients

$SMP=ShadingModelParameters($OPTIONS['ShadingModel']);

$MSP=$SMP['MSP'];

$MSO=$SMP['MSO'];

$MSC=$SMP['MSC'];

//Ground reflectance

$GroundReflectance=$OPTIONS['GroundReflectance'];

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

//CALCULATIONS

//%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

for ($d = 0; $d < $TIME['Ndays']; $d++)

{

for ($h = 0; $h < $TIME['Nsteps']; $h++)

{

// Angles surface following the sun in azimuthal one axis

// Start the ideal value, and then considers whether it should be corrected

$beta_parrilla[$d][$h]=$Inclination_rack*pi()/180;

$alfa[$d][$h]=$fis[$d][$h];

//Calculate the length of the shadow.

if ( abs($w[$d][$h]) >= abs($ws[$d]) )

{

$S1[$d][$h]=0.0000001;

$S2[$d][$h]=0;

}else

{

$S1[$d][$h]=$ALARG*cos($beta_parrilla[$d][$h]);

$S2[$d][$h]=$ALARG*sin($beta_parrilla[$d][$h])*tan($tetazs[$d][$h]);

}

$SP[$d][$h]=$S1[$d][$h]+$S2[$d][$h];

// Consideration of the shadows projected by a tracker located at E.

// geometric:

// Initial set to zero (needed for the program if no shade)

$FSGVE[$d][$h]=0;

$FSGHE[$d][$h]=0;

//Factor calculation when shadow

if ( $w[$d][$h] <= 0 )

{

if ( $fis[$d][$h] < (-pi()/2) )

{

$FSGHE[$d][$h]=max(0,(1-$LEO*cos(pi()-($fis[$d][$h]))));

}else

{

$FSGHE[$d][$h]=max(0,(1-$LEO*cos($fis[$d][$h])));

}

if ( $gammas[$d][$h] > 0.000001 )

{

$FSGVE[$d][$h]=max(0,(1+$LEO/$SP[$d][$h]*sin($fis[$d][$h])));

}

}

$FSGTE[$d][$h]= $FSGVE[$d][$h]*$FSGHE[$d][$h];

//Martinez shading model

$NBSVE[$d][$h]=0;

$NBSHE[$d][$h]=0;

$NBSTE[$d][$h]=0;

$FSEVE[$d][$h]=0;

$FSEHE[$d][$h]=0;

$FSETE[$d][$h]=0;

//Effective values:

if ( $FSGTE[$d][$h] > 0 )

{

$NBSVE[$d][$h] = RoundToZero($FSGVE[$d][$h]* $NBGV+ 0.999);

$NBSHE[$d][$h] = RoundToZero($FSGHE[$d][$h]* $NBGH+ 0.999);

$NBSTE[$d][$h] = $NBSVE[$d][$h] * $NBSHE[$d][$h];

$FSEVE[$d][$h] = $NBSVE[$d][$h]/$NBGV;

$FSEHE[$d][$h] = $NBSHE[$d][$h]/$NBGH;

if ( $MSC == 1 )

{

$FSETE[$d][$h]=$FSEVE[$d][$h]*$FSEHE[$d][$h];

}else

{

$FSETE[$d][$h]=1-(1-$FSGTE[$d][$h])*(1-(1-$MSO)*$NBSTE[$d][$h]/($NBT+1))*(1-$MSP);

}

}

// Consideration of the shadows projected by a tracker located at W.

// geometric:

$FSGVO[$d][$h]=0;

$FSGHO[$d][$h]=0;

if ( $w[$d][$h] >= 0 )

{

if ( $fis[$d][$h] > pi()/2) //To calculate the shade when the sun rises from behind

{

$FSGHO[$d][$h]=max(0,(1-$LEO*cos(pi()-$fis[$d][$h])));

}else

{

$FSGHO[$d][$h]=max(0,(1-$LEO*cos($fis[$d][$h])));

}

if ( $gammas[$d][$h] > 0.0000001 )

{

$FSGVO[$d][$h]=max(0,(1-$LEO/$SP[$d][$h]*sin($fis[$d][$h])));

}

}

$FSGTO[$d][$h]= $FSGVO[$d][$h]*$FSGHO[$d][$h];

//Martinez shading model

$NBSVO[$d][$h]=0;

$NBSHO[$d][$h]=0;

$NBSTO[$d][$h]=0;

$FSEVO[$d][$h]=0;

$FSEHO[$d][$h]=0;

$FSETO[$d][$h]=0;

//Effective values:

if ( $FSGTO[$d][$h] > 0 )

{

$NBSVO[$d][$h] = RoundToZero($FSGVO[$d][$h]* $NBGV+ 0.999);

$NBSHO[$d][$h] = RoundToZero($FSGHO[$d][$h]* $NBGH+ 0.999);

$NBSTO[$d][$h] = $NBSVO[$d][$h] * $NBSHO[$d][$h];

$FSEVO[$d][$h] = $NBSVO[$d][$h]/$NBGV;

$FSEHO[$d][$h] = $NBSHO[$d][$h]/$NBGH;

if ( $MSC == 1 )

{

$FSETO[$d][$h]=$FSEVO[$d][$h]*$FSEHO[$d][$h];

}else

{

$FSETO[$d][$h]=1-(1-$FSGTO[$d][$h])*(1-(1-$MSO)*$NBSTO[$d][$h]/($NBT+1))*(1-$MSP);

}

}

// Consideration of the shadows projected by a tracker located at SE.

// geometric:

//Azimuth at the beginning of the shade

$tanfiscsse= -($LEO+cos($fis[$d][$h]))/($LNS+sin($fis[$d][$h]));

//Azimuth at the end of the shade

$tanfisfsse= -($LEO-cos($fis[$d][$h]))/($LNS-sin($fis[$d][$h]));

//Azimuth horizontal shadow unity

$tanfiss1se= - $LEO/$LNS;

//Initial set to zero

$FSGHSE[$d][$h]=0;

$FSGVSE[$d][$h]=0;

if ( tan($fis[$d][$h]) >= $tanfiscsse )

{

if ( tan($fis[$d][$h]) <= $tanfiss1se )

{

$FSGHSE[$d][$h]=1-($tanfiss1se-tan($fis[$d][$h]))/($tanfiss1se-$tanfiscsse);

$FSGVSE[$d][$h]=max(0,(1-(($LNS*cos($fis[$d][$h])-$LEO*sin($fis[$d][$h]))/$SP[$d][$h])));

}

}

if ( tan($fis[$d][$h]) >= $tanfiss1se )

{

if ( tan($fis[$d][$h]) <= $tanfisfsse )

{

$FSGHSE[$d][$h]=1-(tan($fis[$d][$h])-$tanfiss1se)/($tanfisfsse-$tanfiss1se);

$FSGVSE[$d][$h]=max(0,(1-(($LNS*cos($fis[$d][$h])-$LEO*sin($fis[$d][$h]))/$SP[$d][$h])));

}

}

$FSGTSE[$d][$h]= $FSGVSE[$d][$h]*$FSGHSE[$d][$h];

//Martinez shading model

$NBSVSE[$d][$h]=0;

$NBSHSE[$d][$h]=0;

$NBSTSE[$d][$h]=0;

$FSEVSE[$d][$h]=0;

$FSEHSE[$d][$h]=0;

$FSETSE[$d][$h]=0;

//Effective values:

if ( $FSGTSE[$d][$h] > 0 )

{

$NBSVSE[$d][$h] = RoundToZero($FSGVSE[$d][$h]* $NBGV+ 0.999);

$NBSHSE[$d][$h] = RoundToZero($FSGHSE[$d][$h]* $NBGH+ 0.999);

$NBSTSE[$d][$h] = $NBSVSE[$d][$h] * $NBSHSE[$d][$h];

$FSEVSE[$d][$h] = $NBSVSE[$d][$h]/$NBGV;

$FSEHSE[$d][$h] = $NBSHSE[$d][$h]/$NBGH;

if ( $MSC == 1 )

{

$FSETSE[$d][$h]= $FSEVSE[$d][$h]*$FSEHSE[$d][$h];

}else

{

$FSETSE[$d][$h]=1-(1-$FSGTSE[$d][$h])*(1-(1-$MSO)*$NBSTSE[$d][$h]/($NBT+1))*(1-$MSP);

}

}

// Consideration of the shadows projected by a tracker located at SW.

// geometric:

//Azimuth at the beginning of the shade

$tanfiscsso= ($LEO-cos($fis[$d][$h]))/($LNS+sin($fis[$d][$h]));

//Azimuth at the end of the shade

$tanfisfsso= ($LEO+cos($fis[$d][$h]))/($LNS-sin($fis[$d][$h]));

//Azimuth horizontal shadow unity

$tanfiss1so= $LEO/$LNS;

//Initial set to zero

$FSGHSO[$d][$h]=0;

$FSGVSO[$d][$h]=0;

if ( tan($fis[$d][$h]) >= $tanfiscsso )

{

if ( tan($fis[$d][$h]) <= $tanfiss1so )

{

$FSGHSO[$d][$h]=1-($tanfiss1so-tan($fis[$d][$h]))/($tanfiss1so-$tanfiscsso);

$FSGVSO[$d][$h]=max(0,(1-(($LNS*cos($fis[$d][$h])+$LEO*sin($fis[$d][$h]))/$SP[$d][$h])));

}

}

if ( tan($fis[$d][$h]) >= $tanfiss1so )

{

if ( tan($fis[$d][$h]) <= $tanfisfsso )

{

$FSGHSO[$d][$h]=1-(tan($fis[$d][$h])-$tanfiss1so)/($tanfisfsso-$tanfiss1so);

$FSGVSO[$d][$h]=max(0,(1-(($LNS*cos($fis[$d][$h])+$LEO*sin($fis[$d][$h]))/$SP[$d][$h])));

}

}

$FSGTSO[$d][$h]= $FSGVSO[$d][$h]*$FSGHSO[$d][$h];

//Martinez shading model

$NBSVSO[$d][$h]=0;

$NBSHSO[$d][$h]=0;

$NBSTSO[$d][$h]=0;

$FSEVSO[$d][$h]=0;

$FSEHSO[$d][$h]=0;

$FSETSO[$d][$h]=0;

//Effective values:

if ( $FSGTSO[$d][$h] > 0 )

{

$NBSVSO[$d][$h] = RoundToZero($FSGVSO[$d][$h]* $NBGV+ 0.999);

$NBSHSO[$d][$h] = RoundToZero($FSGHSO[$d][$h]* $NBGH+ 0.999);

$NBSTSO[$d][$h] = $NBSVSO[$d][$h] * $NBSHSO[$d][$h];

$FSEVSO[$d][$h] = $NBSVSO[$d][$h]/$NBGV;

$FSEHSO[$d][$h] = $NBSHSO[$d][$h]/$NBGH;

if ( $MSC == 1 )

{

$FSETSO[$d][$h]=$FSEVSO[$d][$h]*$FSEHSO[$d][$h];

}else

{

$FSETSO[$d][$h]=1-(1-$FSGTSO[$d][$h])*(1-(1-$MSO)*$NBSTSO[$d][$h]/($NBT+1))*(1-$MSP);

}

}

// Consideration of the shadows projected by a tracker located at S.

// geometric:

//Azimuth at the beginning of the shade

$tanfiscss= -1/$LNS;

//Azimuth at the end of the shade

$tanfisfss= 1/$LNS;

//Azimuth horizontal shadow unity

$tanfiss1s= 0;

//Initial set to zero

$FSGHS[$d][$h]=0;

$FSGVS[$d][$h]=0;

if ( abs($w[$d][$h]) < abs($ws[$d]) )

{

if ( tan($fis[$d][$h]) >= $tanfiscss )

{

if ( tan($fis[$d][$h]) <= $tanfiss1s )

{

$FSGHS[$d][$h]=1-($tanfiss1s-tan($fis[$d][$h]))/($tanfiss1s-$tanfiscss);

$FSGVS[$d][$h]=max(0,(1-(($LNS*cos($fis[$d][$h]))/$SP[$d][$h])));

}

}

if ( tan($fis[$d][$h]) >= $tanfiss1s )

{

if ( tan($fis[$d][$h]) <= $tanfisfss )

{

$FSGHS[$d][$h]=1-(tan($fis[$d][$h])-$tanfiss1s)/($tanfisfss-$tanfiss1s);

$FSGVS[$d][$h]=max(0,(1-(($LNS*cos($fis[$d][$h]))/$SP[$d][$h])));

}

}

}

$FSGTS[$d][$h]= $FSGVS[$d][$h]*$FSGHS[$d][$h];

//Martinez shading model

$NBSVS[$d][$h]=0;

$NBSHS[$d][$h]=0;

$NBSTS[$d][$h]=0;

$FSEVS[$d][$h]=0;

$FSEHS[$d][$h]=0;

$FSETS[$d][$h]=0;

//Effective values:

if ( $FSGTS[$d][$h] > 0 )

{

$NBSVS[$d][$h] = RoundToZero($FSGVS[$d][$h]* $NBGV+ 0.999);

$NBSHS[$d][$h] = RoundToZero($FSGHS[$d][$h]* $NBGH+ 0.999);

$NBSTS[$d][$h] = $NBSVS[$d][$h] * $NBSHS[$d][$h];

$FSEVS[$d][$h] = $NBSVS[$d][$h]/$NBGV;

$FSEHS[$d][$h] = $NBSHS[$d][$h]/$NBGH;

if ( $MSC == 1 )

{

$FSETS[$d][$h]=$FSEVS[$d][$h]*$FSEHS[$d][$h];

}else

{

$FSETS[$d][$h]=1-(1-$FSGTS[$d][$h])*(1-(1-$MSO)*$NBSTS[$d][$h]/($NBT+1))*(1-$MSP);

}

}

// Total Shadows (sum of above)

// Geometric:

$FSGTT[$d][$h]=$FSGTE[$d][$h]+$FSGTO[$d][$h]+$FSGTSE[$d][$h]+$FSGTSO[$d][$h]+$FSGTS[$d][$h];

//Effective

$FSETT[$d][$h]=$FSETE[$d][$h]+$FSETO[$d][$h]+$FSETSE[$d][$h]+$FSETSO[$d][$h]+$FSETS[$d][$h];

// Correction azimuth angle by backtracking:

// To avoid shadows projected by a tracker located at E

if ( ($w[$d][$h] <= 0) && ($FSGTE[$d][$h] > 0) )

{

if ( $fis[$d][$h] < -pi()/2 )

{

$alfa[$d][$h]=$fis[$d][$h]+ $RSEV*acos(min(1,$LEO*cos(pi()-$fis[$d][$h])));

}else

{

$alfa[$d][$h]=$fis[$d][$h]+ $RSEV*acos(min(1,$LEO*cos($fis[$d][$h])));

}

}

//To avoid shadows projected by the tracker located at W

if ( ($w[$d][$h] >= 0) && ($FSGTO[$d][$h] > 0) )

{

if ( $fis[$d][$h] > pi()/2 )

{

$alfa[$d][$h]=$fis[$d][$h]- $RSEV*acos(min(1,$LEO*cos(pi()-$fis[$d][$h])));

}else

{

$alfa[$d][$h]=$fis[$d][$h]- $RSEV*acos(min(1,$LEO*cos($fis[$d][$h])));

}

}

// Angle of incidence. For just before dawn, the value of zero for the cosine of the incident angle is set.

// It is a way to eliminate radiation in that period.

// Coordinates of the radius vector of the sun unit in a system of coordinates Oxyz solidarity with the place

// and the x axis X, Y, Z pointing respectively to the west, south and the zenith

$xsol[$d][$h]=cos($gammas[$d][$h])*sin($fis[$d][$h]);

$ysol[$d][$h]=cos($gammas[$d][$h])*cos($fis[$d][$h]);

$zsol[$d][$h]=sin($gammas[$d][$h]);

// UPON ROTATION OF HORIZONTAL AXIS

// Unit coordinates of the radius vector of the sun in a coordinate system Ox'y'z 'integral with the follower

// and the x axis X', Y ', Z' pointing respectively to the horizontal direction of the row, to perpendicular

// to the row direction and the zenith

$xprimasol[$d][$h] = $xsol[$d][$h]*cos($alfa[$d][$h]) - $ysol[$d][$h]*sin($alfa[$d][$h]);

$yprimasol[$d][$h] = $xsol[$d][$h]*sin($alfa[$d][$h]) + $ysol[$d][$h]*cos($alfa[$d][$h]);

$zprimasol[$d][$h] = $zsol[$d][$h];

//Ideal inclination angle. Only works when the sun is ahead

//(yprimasol >=0 )

if ( ($yprimasol[$d][$h] > 0) && ($zprimasol[$d][$h] > 0) )

{

$beta_ideal[$d][$h]=atan($yprimasol[$d][$h]/$zprimasol[$d][$h]);

}else

{

$beta_ideal[$d][$h]=$beta_parrilla[$d][$h];

}

// Consideration of shadows

// Initial set to zero

$FSGFHN[$d][$h]=0;

//FSGFVN[$d][$h]=0;

//Length of the shadow on the support of the grid

$SPARRILLA[$d][$h] = 1/cos($beta_ideal[$d][$h]-$beta_parrilla[$d][$h]);

// Consideration of whether it is day shadows (zprimasol> 0) and the sun is in front (yprimasol> 0)

if ( ($yprimasol[$d][$h] > 0) && ($zprimasol[$d][$h] > 0) )

{

// Factor shade of the row (the name now includes an "F" row) in the vertically projected by the row that is to N

$FSGFVN[$d][$h]=max(0,(1-$LNS_rack/$SPARRILLA[$d][$h]));

//Shade factor row in the horizontal direction

if ( $xprimasol[$d][$h] == 0 )

{

$FSGFHN[$d][$h] = 1;

}elseif ($xprimasol[$d][$h] > 0)

{

$FSGFHN[$d][$h]= max(0,(1-($LNS_rack*cos($beta_parrilla[$d][$h])-$ALARGF*cos($beta_ideal[$d][$h]))*($yprimasol[$d][$h]/$xprimasol[$d][$h])));

}elseif ($xprimasol[$d][$h] < 0 )

{

$FSGFHN[$d][$h]= max(0,(1+($LNS_rack*cos($beta_parrilla[$d][$h])-$ALARGF*cos($beta_ideal[$d][$h]))*($yprimasol[$d][$h]/$xprimasol[$d][$h])));

}

}else

{

$FSGFVN[$d][$h] = 0;

$FSGFHN[$d][$h] = 0;

}

$FSGFTN[$d][$h]= $FSGFVN[$d][$h]*$FSGFHN[$d][$h];

// MODELS OF SHADOWS (THE NOMENCLATURE RESULTS OF ADDING AN "F" ROW)

$NBSFVN[$d][$h]=0;

$NBSFHN[$d][$h]=0;

$NBSFTN[$d][$h]=0;

$FSEFVN[$d][$h]=0;

$FSEFHN[$d][$h]=0;

$FSEFTN[$d][$h]=0;

//Effective values:

if ($FSGFTN[$d][$h] > 0)

{

$NBSFVN[$d][$h] = RoundToZero($FSGFVN[$d][$h]* $NBFV+ 0.999);

$NBSFHN[$d][$h] = RoundToZero($FSGFHN[$d][$h]* $NBGH+ 0.999);

$NBSFTN[$d][$h] = $NBSFVN[$d][$h] * $NBSFHN[$d][$h];

$FSEFVN[$d][$h] = $NBSFVN[$d][$h]/$NBFV;

$FSEFHN[$d][$h] = $NBSFHN[$d][$h]/$NBGH;

if ($MSC == 1)

{

$FSEFTN[$d][$h]=$FSEFVN[$d][$h]*$FSEFHN[$d][$h];

}else

{

$FSEFTN[$d][$h]=1-(1-$FSGFTN[$d][$h])*(1-(1-$MSO)*$NBSTS[$d][$h]/($NBFV*$NBGH+1))*(1-$MSP);

}

}

//Consideration of the horizontal axis backtracking

$beta[$d][$h] = $beta_ideal[$d][$h]- $RSEH*acos(min(1 , $LNS_rack/$SPARRILLA[$d][$h]));

// Coordinates of the normal to the surface in the same previous coordinate system

$xsup[$d][$h]=sin($beta[$d][$h])*sin($alfa[$d][$h]);

$ysup[$d][$h]=sin($beta[$d][$h])*cos($alfa[$d][$h]);

$zsup[$d][$h]=cos($beta[$d][$h]);

//Incidence angle

if ( abs($w[$d][$h]) >= abs($ws[$d]) )

{

$costetas[$d][$h]=1;

}else

{

$costetas[$d][$h]=$xsol[$d][$h]*$xsup[$d][$h]+$ysol[$d][$h]*$ysup[$d][$h]+$zsol[$d][$h]*$zsup[$d][$h];

}

//Direct component

//Resets direct predawn (redundant with the previous statement) and posterior incidence

if ( abs($w[$d][$h]) >= abs($ws[$d]) )

{

$B[$d][$h]=0;

}else

{

$B[$d][$h]=$B0[$d][$h]*max(0,$costetas[$d][$h])/$costetazs[$d][$h];

}

//Isotropic, circumsolar and horizon components of the diffuse irradiation

if ( abs($w[$d][$h]) >= abs($ws[$d]) )

{

$Diso[$d][$h]=0;

$Dcir[$d][$h]=0;

$Dhor[$d][$h]=0;

$D[$d][$h]=0;

}else

{

$Diso[$d][$h]=$D0[$d][$h]*(1-$k1[$d][$h])*(1+cos($beta[$d][$h]))/2;

$Dcir[$d][$h]=$D0[$d][$h]*$k1[$d][$h]*max(0,$costetas[$d][$h])/$costetazs[$d][$h];

$Dhor[$d][$h]=$D0[$d][$h]*$k2[$d][$h]*sin($beta[$d][$h]);

$D[$d][$h]=$Diso[$d][$h]+$Dcir[$d][$h]+$Dhor[$d][$h];

}

//Albedo component

if ( abs($w[$d][$h]) >= abs($ws[$d]) )

{

$R[$d][$h]=0;

}else

{

$R[$d][$h]=$GroundReflectance*$G0[$d][$h]*(1-cos($beta[$d][$h]))/2;

}

//Global irradiance

$G[$d][$h]=$B[$d][$h]+$D[$d][$h]+$R[$d][$h];

// Consideration of the effects of the incidence angle

// Correction of the directly irradiation factor

$FCB[$d][$h]=(1-exp(-$costetas[$d][$h]/$ar))/(1-exp(-1/$ar));

//Correction of the diffuse irradiation factor

$FCD[$d][$h]=1-exp(-1/$ar*((sin($beta[$d][$h])+(pi()-$beta[$d][$h]-sin($beta[$d][$h]))/(1+cos($beta[$d][$h])))*4/3/pi()+$c2*pow(sin($beta[$d][$h])+(pi()-$beta[$d][$h]-sin($beta[$d][$h]))/(1+cos($beta[$d][$h])),2)));

//Correction of the albedo factor

if ( $beta[$d][$h] == 0 )

{

$FCR[$d][$h]=0;

}else

{

$FCR[$d][$h]=1-exp(-1/$ar*((sin($beta[$d][$h])+($beta[$d][$h]-sin($beta[$d][$h]))/(1-cos($beta[$d][$h])))*4/3/pi()+$c2*pow(sin($beta[$d][$h])+($beta[$d][$h]-sin($beta[$d][$h]))/(1-cos($beta[$d][$h])),2)));

}

//Effective irradiation components

$Bef[$d][$h]=$B[$d][$h]*$FCB[$d][$h]*$Transm;

$Def[$d][$h]=(($Diso[$d][$h]+$Dhor[$d][$h])*$FCD[$d][$h]+$Dcir[$d][$h]*$FCB[$d][$h])*$Transm;

$Ref[$d][$h]=$R[$d][$h]*$FCR[$d][$h]*$Transm;

//Effective irradiance

$Gef[$d][$h]=$Bef[$d][$h]+$Def[$d][$h]+$Ref[$d][$h];

// Effective irradiance after adjacent shadows (E + W)

// Maximum limitation shadow factor to the unit

$FSET[$d][$h]=min(1, $FSETE[$d][$h]+$FSETO[$d][$h]);

$Befsa[$d][$h]=(1-$FSET[$d][$h]*(1-$RSEV))*$Bef[$d][$h];

//$Befsa[$d][$h]=(1-($FSETE[$d][$h]+$FSETO[$d][$h])*(1-$RSEV))*$Bef[$d][$h];

$Defsa[$d][$h]=(($Diso[$d][$h]+$Dhor[$d][$h])*$FCD[$d][$h]+$Dcir[$d][$h]*$FCB[$d][$h]*(1-$FSET[$d][$h]*(1-$RSEV)))*$Transm;

//$Defsa[$d][$h]=(($Diso[$d][$h]+$Dhor[$d][$h])*$FCD[$d][$h]+$Dcir[$d][$h]*$FCB[$d][$h]*(1-($FSETE[$d][$h]+$FSETO[$d][$h])*(1-$RSEV)))*$Transm;

$Gefsa[$d][$h]=$Befsa[$d][$h]+$Defsa[$d][$h]+$Ref[$d][$h];

//Total effective irradiance after shadows(E + W + SE + SW) and shading between rows

//Maximum limitation shadow factor to the unit

$FSETT[$d][$h]=min(1, $FSETE[$d][$h]+$FSETO[$d][$h]+$FSETSE[$d][$h]+$FSETSO[$d][$h]);

$FSEFTN[$d][$h]=min(1, $FSEFTN[$d][$h]);

$Befsayp[$d][$h]=(1-$FSETT[$d][$h]*(1-$RSEV))*(1-$FSEFTN[$d][$h]*(1-$RSEH))*$Bef[$d][$h];

//$Befsayp[$d][$h]=(1-($FSETE[$d][$h]+$FSETO[$d][$h]+$FSETSE[$d][$h]+$FSETSO[$d][$h])*(1-$RSEV))*(1-$FSEFTN[$d][$h]*(1-$RSEH))*$Bef[$d][$h];

$Defsayp[$d][$h]=(($Diso[$d][$h]+$Dhor[$d][$h])*$FCD[$d][$h]+$Dcir[$d][$h]*$FCB[$d][$h]*(1-$FSETT[$d][$h]*(1-$RSEV)*(1-$FSEFTN[$d][$h]*(1-$RSEH))))*$Transm;

//$Defsayp[$d][$h]=(($Diso[$d][$h]+$Dhor[$d][$h])*$FCD[$d][$h]+$Dcir[$d][$h]*$FCB[$d][$h]*(1-($FSETE[$d][$h]+$FSETO[$d][$h]+$FSETSE[$d][$h]+$FSETSO[$d][$h])*(1-$RSEV)*(1-$FSEFTN[$d][$h]*(1-$RSEH))))*$Transm;

$Gefsayp[$d][$h]=$Befsayp[$d][$h]+$Defsayp[$d][$h]+$Ref[$d][$h];

}//end FOR $h Nsteps

}//end FOR $d Ndays

$ISI= array (

'G' => $G,

'B' => $B,

'D' => $D,

'R' => $R,

'Gef' => $Gef,

'Bef' => $Bef,

'Def' => $Def,

'Ref' => $Ref,

'Gefsa' => $Gefsa,

'Befsa' => $Befsa,

'Defsa' => $Defsa,

'Gefsayp' => $Gefsayp,

'Befsayp' => $Befsayp,

'Defsayp' => $Defsayp);

return $ISI;