The behavior of certain calculation functions is slightly different in Polaris compared to the Classic Engine. Additionally, you cannot use some functions in Polaris.
Functions with differences between engines
Calculation function  Difference 
ALL aggregation function  In Polaris, the calculated result is TRUE for cells not mapped. In the Classic Engine, the default value is FALSE. 
ADDMONTHS  In Polaris, if you use a value of NaN (Not a Number) for the Number argument, the ADDMONTHS function returns a blank value. In the Classic Engine, a value of NaN used with ADDMONTHS is equivalent to 0. 
ADDYEARS  In Polaris, if you use a value of NaN (Not a Number) for the Number argument, the ADDYEARS function returns a blank value. In the Classic Engine, a value of NaN used with ADDYEARS is equivalent to 0. 
AVERAGE aggregation function  In Polaris, you cannot use the bracketed aggregation function AVERAGE in formulas of line items with a formula summary method. In the Classic Engine, you can. 
CODE  In Polaris, if you use a time period value for the Item argument, the CODE function returns a blank text result. In the Classic Engine, if you use a time period value for the Item argument, the CODE function returns the time period value as text. 
CUMULATE  In Polaris, you cannot use CUMULATE in formulas of line items with a formula summary method. In the Classic Engine, you can. In Polaris, the List argument must identically match a dimension of the line item to which the formula is applied. In the Classic Engine, you can also use a subset of a line item dimension as List. 
DECUMULATE  In Polaris, you cannot use DECUMULATE in formulas of line items with a formula summary method. In the Classic Engine, you can. 
FIND  In Polaris, the FIND function considers the length of all Unicode characters to be one. This means that the FIND function returns the correct starting character. In the Classic Engine, the FIND function considers the length of:

FINDITEM  In Polaris, you cannot use the FINDITEM function with one Time argument. In the Classic Engine, you can use FINDITEM with one or two Time arguments. 
HALFYEARTODATE  In Polaris, you can use the HALFYEARTODATE function with line items with a time scale of HalfYear. In the Classic Engine, you cannot. In Polaris, you cannot use HALFYEARTODATE in formulas of line items with a formula summary method. In the Classic Engine, you can. 
HALFYEARVALUE  In Polaris, you must enable Halfyear Totals in the Model Calendar to use the HALFYEARVALUE function. In the Classic Engine, you can use the HALFYEARVALUE function regardless of if Halfyear Totals is enabled in the Model Calendar. In Polaris, you cannot use the HALFYEARVALUE function in a result line item with a time scale greater than the function. The Classic Engine returns a value of 0 in this case. 
ISANCESTOR  In Polaris, the ISANCESTOR function returns a value of false when given a top level item coupled with an orphan entity. In the Classic Engine, this will return a value of true. 
ISBLANK  In Polaris, the ISBLANK function considers a text value that consists exclusively of carriage return characters to be a blank value. In the Classic Engine, the ISBLANK function considers a carriage return to be a nonblank value. 
ISFIRSTOCCURRENCE  Note: Performance of ISFIRSTOCCURRENCE is known to be poor in Polaris for high dimensionality. It's strongly advised to avoid ISFIRSTOCCURRENCE in Polaris. In Polaris, you can use the ISFIRSTOCCURRENCE function with the Time list. In the Classic Engine, you cannot. Also in Polaris, the ISFIRSTOCCURRENCE function does not have a 50 million cell limit as it does in the Classic Engine. 
ISNOTBLANK  In Polaris, the ISNOTBLANK function considers a text value that consists exclusively of carriage return characters to be a blank value. In the Classic Engine, the ISNOTBLANK function considers a carriage return to be a nonblank value. 
ITEM  In Polaris, you cannot use ITEM in formulas of line items with formula summary method. In the Classic Engine, you can. In Polaris, you cannot use the ITEM function with one Time argument. In the Classic Engine, you can. 
LAG  In Polaris, the Offset amount argument rounds to the nearest whole number. In the Classic Engine, the Offset amount argument rounds towards zero. In the Classic Engine, you can use the LAG function only with a time dimension. In Polaris, you can use LAG with any dimension except Versions. 
LEAD  In Polaris, the Offset amount argument rounds to the nearest whole number. In the Classic Engine, the Offset amount argument rounds towards zero. In the Classic Engine, you can use the LEAD function only with a time dimension. In Polaris, you can use LEAD with any dimension except Versions. 
LEFT  In Polaris, the LEFT function behaves as expected with all text values, including those that contain composite characters or characters from outside the Basic Multilingual Plane (BMP). In the Classic Engine, the LEFT function considers the length of:

LENGTH  In Polaris, the LENGTH function behaves as expected with all text values, including those that contain composite characters or characters from outside the Basic Multilingual Plane (BMP). In the Classic Engine, the LENGTH function considers the length of:

LOG  In Polaris, the LOG function returns a value of NaN (Not a Number) if you use positive infinity for the Base argument. In the Classic Engine, the LOG function returns 0 if you use positive infinity for the Base argument. 
LOOKUP  In Polaris, you cannot use the LOOKUP function in a result line item with a time scale greater than the values you look up. The Classic Engine returns a value of 0 in this case. In Polaris, an invalid LOOKUP is rejected where the Mapping is dimensioned by a line item the formula is set on, and the values to look up are not dimensioned by that subset. 
LOWER  In Polaris, you cannot use the Locale argument with the LOWER function. In the Classic Engine, you can use the Locale argument. 
MAX aggregation function  In Polaris, you cannot use the bracketed aggregation function MAX in formulas of line items with a formula summary method. In the Classic Engine, you can. 
MID  In Polaris, the MID function behaves as expected with all text values, including those that contain composite characters or characters from outside the Basic Multilingual Plane (BMP). In the Classic Engine, the MID function considers the length of:

MIN  In Polaris, when comparing a blank date value to a nonblank date value, the MIN function returns the nonblank value. In the Classic Engine, when comparing a blank date value to a nonblank date value, the MIN function returns the blank value. 
MIN aggregation function  In Polaris, when comparing a blank date value to a nonblank date value, the MIN function returns the nonblank value. In the Classic Engine, when comparing a blank date value to a nonblank date value, the MIN function returns the blank value. For dates, blank cells calculate to blank for Polaris and 23991231 for the Classic Engine. For numbers, blank cells calculate to 0 for Polaris and positive infinity for the Classic Engine. In Polaris, you cannot use the bracketed aggregation function MIN in formulas of line items with a formula summary method. In the Classic Engine, you can. 
MONTHTODATE  In Polaris, you can use the MONTHTODATE function with line items with a time scale of Month. In the Classic Engine, you cannot. In Polaris, you cannot use MONTHTODATE in formulas of line items with a formula summary method. In the Classic Engine, you can. 
MONTHVALUE  In Polaris, you cannot use the MONTHVALUE function in a result line item with a time scale greater than the function. The Classic Engine returns a value of 0 in this case. 
MOVINGSUM  In Polaris, you cannot use MOVINGSUM in formulas of line items with a formula summary method. In the Classic Engine, you can. 
MROUND  In Polaris, if Number of decimal places resolves to NaN (Not a Number) or 0, then the MROUND function returns 0. In the Classic Engine, this returns NaN. 
NEXT  In Polaris, you cannot use NEXT in formulas of line items with a formula summary method. In the Classic Engine, you can. For time outside the time range hierarchy, Polaris returns zero or blank values. In the Classic Engine, NEXT can apply to a time outside the time range hierarchy. In the Classic Engine, you can use the NEXT function only with a time dimension. In Polaris, you can use NEXT with any dimension except Versions. For Versions, use NEXTVERSION. 
OFFSET  In Polaris, a value of NaN (Not a Number) for the Offset amount argument returns the Substitute value argument. In the Classic Engine, a value of NaN is equivalent to 0. In the Classic Engine, you can use the OFFSET function only with a time dimension. In Polaris, you can use OFFSET with any dimension except Versions. 
Operators and constants  In Polaris, operators such as >, <, and = return a value of FALSE when used with blank date or time period values. In the Classic Engine, a nonblank date or time period value is greater than a blank date or time period value. In Polaris, operators such as >, <, and = are tolerant of small differences to 1E14. In the Classic Engine, the operators are exact. For arithmetic operators + and , Polaris returns a blank date when any date operands are blank. In the Classic Engine, a blank date assumes the minimum possible value. For arithmetic operator *, Polaris returns 0 when any operands are NaN (Not a Number). The Classic Engine returns NaN. 
PARENT  In Polaris, the parent of Years within the Time list is All Periods. In the Classic Engine, All Periods has a time scale of Years, which means Years is the parent of Years. In Polaris, the results of formulas are not coerced into different timescales. For example, if a formula returns a result with a Months timescale in a line item with the Years timescale, the formula is invalid. In the Classic Engine, the results of formulas are coerced into different timescales. For example, if a formula returns a result with a Months timescale in a line item with the Years timescale, the Months value automatically converts to display in the Years line item. 
PERIOD  In Polaris, you can only use PERIOD in a line item that has a Type of Time Period. The result has the same timescale as the line item type. 
POST  In Polaris, you cannot use POST in formulas of line items with a formula summary method. In the Classic Engine, you can. 
POWER  In Polaris, In the Classic Engine, 
PREVIOUS  In Polaris, you cannot use PREVIOUS in formulas of line items with a formula summary method. In the Classic Engine, you can. In the Classic Engine, you can use the PREVIOUS function only with a time dimension. In Polaris, you can use PREVIOUS with any dimension. 
PROFILE  In Polaris, the lookup dimension cannot relate to any dimension of the line item to which the formula is applied. In Polaris, you cannot use PROFILE in formulas of line items with a formula summary method. In the Classic Engine, you can. 
QUARTERTODATE  In Polaris, you can use the QUARTERTODATE function with line items with a time scale of Quarter. In the Classic Engine, you cannot. In Polaris, you cannot use QUARTERTODATE in formulas of line items with a formula summary method. In the Classic Engine, you can. 
QUARTERVALUE  In Polaris, you must enable Quarter Totals in the Model Calendar to use the QUARTERVALUE function. In the Classic engine, you can use the QUARTERVALUE function regardless of if Quarter Totals is enabled in the Model Calendar. In Polaris, you cannot use the QUARTERVALUE function in a result line item with a time scale greater than the function. The Classic Engine returns a value of 0 in this case. 
RANK  You cannot use RANK in Polaris, if:
In Classic, a value of FALSE for the Include value argument omits a value from the ranking and returns a result of NaN (Not a Number). In Polaris it returns a value of 0 (zero). In Classic, you can use a text data type for the Ranking groups argument. In Polaris, you cannot. In Polaris you do not have a cell limit. In Classic, it is 50 million cells. In Classic, infinities and NaN are automatically excluded from the RANK function and return a result of NaN. In Polaris, NaN values are automatically excluded from the RANK function and return a result of 0. Infinities have also been removed. 
RANKCUMULATE  In Polaris, RANKCUMULATE can not be used when the target is dimensioned by a line item subset, or the function makes a reference to a line item subset. In Polaris you do not have a cell limit. In Classic, it is 50 million cells. Polaris does not support infinities, in Classic it does. In Classic, if a cumulation source contains an Infinity, then the result from then on until the end of the cumulation is that infinity. However, if an opposite Infinity follows it, the result becomes NaN (Not a Number). In Polaris it will return NaN instead of Infinity. In Polaris, blank is unordered , so it is unrankable. For RANKCUMULATE, if the ranking value is blank the the function returns zero. In Polaris, the ranking values can be the BLANK literal, this is, 
RIGHT  In Polaris, the RIGHT function behaves as expected with all text values, including those that contain composite characters or characters from outside the Basic Multilingual Plane (BMP). In the Classic Engine, the RIGHT function considers the length of:

ROUND  In Polaris, the ROUND function always uses the EXACT rounding method. As such, you cannot provide the Rounding method argument. In the Classic engine, the ROUND function uses the NORMAL rounding method unless you provide EXACT for the Rounding method argument. In Polaris, if Number to round is 0 and Number of decimal places is NaN (Not a Number), then the ROUND function returns 0. In the Classic Engine, this returns NaN. In Polaris, if Number to round is not 0 and Number of decimal places is NaN (Not a Number), then the ROUND function returns NaN. In the Classic Engine, this returns NaN. In Polaris, if Number of decimal places is not a whole number, then Number of decimal places rounds to the nearest whole number. The Classic Engine does not support the NORMAL Rounding method in this case, and with the EXACT Rounding method, ROUND rounds towards zero. In Polaris, if Number of decimal places is Infinity or less than 308.5, then ROUND returns 0, Infinity, or Infinity, as expected. If Number of decimal places is Infinity or greater than 308.5, then ROUND returns Number to round. In the Classic Engine, all these return NaN (Not a Number). In Polaris, if Rounding direction is UP, DOWN, AWAYFROMZERO, or TOWARDSZERO, and the result is too small to represent, then ROUND returns the smallest possible number. In the Classic Engine, these cases, with a Rounding method of EXACT, return 0. In Polaris, if Number to round is negative, Rounding direction is NEAREST, and Number of decimal places is negative, then ROUND rounds away from zero. The Classic Engine rounds this towards zero. 
SELECT  In Polaris, the reference in SELECT must be literal, rather than an expression. In the Classic Engine, SELECT allows expressions only on the time axis, for Time.'Current Period' and literal offsets. 
SPREAD  In Polaris, you cannot use SPREAD in formulas of line items with a formula summary method. In the Classic Engine, you can. 
SUBSTITUTE  In Polaris, the SUBSTITUTE function does not match the base characters of a composite characters. For example, the SUBSTITUTE function does not consider â to contain a or が to contain か. In the Classic Engine, the SUBSTITUTE function matches the base characters of composite characters. For example, the SUBSTITUTE function considers â to contain a or が to contain か. 
SUM aggregation function  In Polaris, you cannot use the bracketed aggregation function SUM in formulas of line items with a formula summary method. In the Classic Engine, you can. 
TEXT  In Polaris, the TEXT function returns a text value of NaN (Not a Number) when used with the numerical value NaN. In the Classic Engine, the TEXT function returns a blank value when you use it with the numerical value NaN. 
TIMESUM  In Polaris you can only use a number or Boolean type for the Line item, to aggregate arguments. In Classic, you can use number, Boolean, date, list, and text type line items. In Polaris, if you only provide a value for the Start period argument and not the End period argument, the TIMESUM function aggregates all values from the Start period through to the end of the applicable time range. In Classic it will just return the value from the Start period. In Polaris, when you use date values for the Start period and End period arguments, they behave as expected. In Classic, the date for the Start period should be in the period where aggregation ends and the date for the End period should be in the period where aggregation begins. In Polaris, if Start period or End period are outside the range of the time dimension, then TIMESUM returns 0. 
TRIM  You cannot currently use the TRIM function in Polaris. In the Classic Engine, the TRIM function removes all leading and trailing spaces, and extra spaces between words in a text string. 
UPPER  In Polaris, you cannot use the Locale argument with the UPPER function. In the Classic Engine, you can use the Locale argument. 
VALUE  In Polaris, the VALUE function returns NaN (Not a Number) for nondecimal representations of numbers (for example, In the Classic Engine, non decimal representations of numbers do not necessarily return NaN. 
WEEKDAY  In Polaris, you can use a decimal value for the Day offset argument and it rounds to the nearest whole number. If you use a value outside of 1 to 7, the function returns a value of 0. In the Classic Engine, you must use a whole number for the Day offset argument. 
WEEKTODATE  In Polaris, you can use the WEEKTODATE function with line items with a time scale of Week. In the Classic Engine, you cannot. In Polaris, you cannot use WEEKTODATE in formulas of line items with a formula summary method. In the Classic Engine, you can. 
WEEKVALUE  In Polaris, you cannot use the WEEKVALUE function in a result line item with a time scale greater than the function. The Classic Engine returns a value of 0 in this case. 
YEARTODATE  In Polaris, you can use the YEARTODATE function with line items with a time scale of Year. In the Classic Engine, you cannot. In Polaris, you cannot use YEARTODATE in formulas of line items with a formula summary method. In the Classic Engine, you can. 
YEARVALUE  In Polaris, you cannot use the YEARVALUE function in a result line item with a time scale greater than the function. The Classic Engine returns a value of 0 in this case. In Polaris, you cannot use YEARVALUE in formulas of line items with a formula summary method. In the Classic Engine, you can. 
Differences with many functions
Arguments
In the Polaris engine, resolved values for whole number arguments round to the nearest integer. Values with a 0.5 fraction round away from zero. For example, 0.5 rounds up, and 0.5 rounds down. In the Classic Engine, the rounding policy depends on the function.
Functions not available in Polaris
Some functions, including most of the call center planning and financial functions are not available in Polaris. These include:
 AGENTS
 AGENTSB
 ANSWERTIME
 ARRIVALRATE
 AVGDURATION
 AVGWAIT
 COMPARE
 COUPDAYBS
 COUPDAYS
 COUPDAYSNC
 COUPNCD
 COUPNUM
 COUPPCD
 DURATION
 ERLANGB
 ERLANGC
 FIRSTNONBLANK aggregation function
 IRR
 LASTNONBLANK aggregation function
 MAILTO
 MAKELINK
 MDURATION
 NPV
 PRICE
 RANK
 RANKCUMULATE
 RATE
 SLA
 TEXTLIST aggregation function
 TEXTLIST calculation function
 TRIM
 YEARFRAC
 YIELD