SHRIMP: Sub StdElePpm

SQUID 2.50 Sub: StdElePpm

The subroutine evaluates, on an analysis-by-analysis basis, the concentration of the 'primary' parent element (usually U, but can be Th, and it is also possible for the user to specify 'No U or Th concentration', whereupon this subroutine is exited).

Usage

StdElePpm(Std, SpotRow)

Mandatory variables

Std: Boolean input which dictates, for each specific invocation of StdElePpm, whether the analysis is that of a 'primary-ratio' reference material, or not.

SpotRow: Index number of the output-row, to which the value calculated by StdElePpm is to be written.

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Definition of variables

Values of type Boolean
Std

Values of type Integer
c, p, SpotRow

Values of type Double
v, pdMeanParentEleA, pdConcStdPpm

Vectors comprising values of type Double
BkrdCPS, count_time_sec, NetCps, TotCps

Arrays comprising values of type Double
AbsNetPkCps, NetPkCps, PkCounts, PkCps, PkFerr, SBMCounts, SBMCps, time_stamp_sec, TrimMass, TrimTime

Arrays comprising values of type String
psaSpotNames, psaSpotDateTime

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The function of the subroutine is paraphrased as follows:

--Recalling that Std = -1 if TRUE, 0 if FALSE, use 
--p and c to define sheet/column for output
p = -Std  

If pbUconcstd = TRUE --if user-defined primary element is U  
  c = piaPpmUcol[p]    
Else  
  c = piaPpmThcol[p]   
End If  

--Note that if user selected "No U or Th Std", then c = 0:  
If c = 0  
  Exit Sub  
End If

If the code reaches this point, then the arithmetic is performed by reference to pdMeanParentEleA, which was calculated in Sq2.50 Procedure Pt 1. Note that piLwrIndx simply refers to the EqNum with the lowest numeric value i.e. piLwrIndx = - 4 (corresponding to the expression for the 'primary parent' concentration constant) for SQUID 2.50 Tasks for U-Th-Pb geochronology. (Ludwig uses the variable piLwrIndx because SQUID 2.50 allows 'non-geochronology' Tasks, which are characterised by the absence of all 'built-in' expressions; in those Tasks (which are outside our scope), all user-defined expressions are 'custom' and piLwrIndx = 1). The code proceeds:

If pdMeanParentEleA > 0 AND pdMeanParentEleA <> SQUID_Error_Value
  --define the address for the output:  
  piSpotOutputCol = piaEqCol[Std, piLwrIndx]  

  EqnInterp Task.Eqns[piLwrIndx], piLwrIndx, v, 0, 1, 0  
  --Note that Calamari already does this arithmetic, without context  
 
  If v = SQUID_Error_Value  
    Exit Sub  
  End If  
  
  --pdConcStdPpm is the reference/model ppm value for the primary element,
  --in the concentration reference material. In our demo XML, that material  
  --has the prefix 'M257', and its model U value is 840 ppm.  
  
  v = v / pdMeanParentEleA * pdConcStdPpm  
End If  

If v > 0  
  --CFs fills the target cell 
  --fsS converts double-precision number to string (not sure why)
  CFs SpotRow, c, fsS(v)  
End If  

End Sub