XML: Macros - Extracting Digits

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Extract Digits Macro

Quite frequently it is necessary to extract the nth digit of a number for any number of reasons. This XML Macro is very handy for the purpose, as it is "universal" and does not care what the number is...

<Macro Name="ExtDigit"> 
@1 sp0 
@3 0 >  
if{ l0 10 @3 pow * sp0 } 
l0 int 10 @2 pow % 10 @2 1 - 0 max pow / int  

(ALGVar) is the A,L or G var from where to extract the digit 
nDigit is the position of the digit to extract, starting from the right. 
nDecimals is the number of decimals to be included in the calcs. 

For instance
for a value of 123.456789999999 

@ExtDigit(lVar,1,0) means I want to extract the right most, discarding the decimals. It returns 3 
@ExtDigit(lVar,2,0) returns 2 ; 
@ExtDigit(lVar,3,0) returns 1 and 
@ExtDigit(lVar,4,0) and up returns 0 

using decimals: 
@ExtDigit(lVar,1,2) returns 5  
@ExtDigit(lVar,2,2) returns 4  
@ExtDigit(lVar,3,2) returns 3  
@ExtDigit(lVar,4,2) returns 2  


1. @1 sp0 - this s(tores) the value of @1 in register 0 (zero) and p(ops) the number from the stack
2. l0 - this is a lower case L, and not a 1 (one)! This means l(oad) the value from the 0 (zero) register
3. @1 @2 @3 - this is how an @Macro passes parameters. The @1 is the first parameter passed from it, etc. Used like so:
    @1 passes Param1 
    @2 passes Param2
    @3 passes Param3