To provide improved function accuracy, consistent functionality that meets expectations, and function names that more accurately describe their functionality, several functions have been updated, renamed, or added to the function library in Microsoft Excel for Mac 2011.
For backward compatibility, renamed functions remain available with their old name.
Algorithm and accuracy improvements
For the following functions, algorithm changes have been implemented to improve function accuracy and performance. For example, a new algorithm has been implemented for the BETADIST function to improve the accuracy of this function. The MOD function now uses new algorithms to achieve both accuracy and speed, and the RAND function now uses a new random number algorithm.
Improved function 
Function category 
Purpose 
Math and trigonometry functions 
Returns the inverse hyperbolic sine of a number 

Statistical functions 
Returns the beta cumulative distribution function 

Compatibility functions 
Returns the beta cumulative distribution function 

Statistical functions 
Returns the inverse of the cumulative distribution function for a specified beta distribution 

Compatibility functions 
Returns the inverse of the cumulative distribution function for a specified beta distribution 

Statistical functions 
Returns the individual term binomial distribution probability 

Compatibility functions 
Returns the individual term binomial distribution probability 

Statistical functions 
Returns the smallest value for which the cumulative binomial distribution is less than or equal to a criterion value 

Math and trigonometry functions 
Rounds a number to the nearest integer or to the nearest multiple of significance 

Compatibility functions 
Returns the smallest value for which the cumulative binomial distribution is less than or equal to a criterion value 

Statistical functions 
Returns the inverse of the onetailed probability of the chisquared distribution 

Compatibility functions 
Returns the inverse of the onetailed probability of the chisquared distribution 

Statistical functions 
Returns the test for independence 

Compatibility functions 
Returns the test for independence 

Engineering functions 
Converts a number from one measurement system to another 

Financial functions 
Returns the cumulative interest paid between two periods 

Financial functions 
Returns the cumulative principal paid on a loan between two periods 

Engineering functions 
Returns the error function 

Engineering functions 
Returns the complementary error function 

Statistical functions 
Returns the F probability distribution 

Compatibility functions 
Returns the F probability distribution 

Compatibility functions 
Returns the inverse of the F probability distribution 

Statistical functions 
Returns the inverse of the F probability distribution 

Math and trigonometry functions 
Returns the double factorial of a number 

Math and trigonometry functions 
Rounds a number down, toward zero 

Statistical functions 
Returns the gamma distribution 

Compatibility functions 
Returns the gamma distribution 

Statistical functions 
Returns the inverse of the gamma cumulative distribution 

Compatibility functions 
Returns the inverse of the gamma cumulative distribution 

Statistical functions 
Returns the natural logarithm of the gamma function, Γ(x) 

Statistical functions 
Returns the geometric mean 

Statistical functions 
Returns the hypergeometric distribution 

Compatibility functions 
Returns the hypergeometric distribution 

Engineering functions 
Returns the base2 logarithm of a complex number 

Engineering functions 
Returns a complex number raised to an integer power 

Financial functions 
Returns the interest payment for an investment for a given period 

Financial functions 
Returns the internal rate of return for a series of cash flows 

Statistical functions 
Returns the parameters of a linear trend 

Compatibility functions 
Returns the cumulative lognormal distribution 

Statistical functions 
Returns the cumulative lognormal distribution 

Statistical functions 
Returns the inverse of the lognormal cumulative distribution 

Compatibility functions 
Returns the inverse of the lognormal cumulative distribution 

Math and trigonometry functions 
Returns the remainder from division 

Statistical functions 
Returns the negative binomial distribution 

Compatibility functions 
Returns the negative binomial distribution 

Statistical functions 
Returns the normal cumulative distribution 

Compatibility functions 
Returns the normal cumulative distribution 

Statistical functions 
Returns the inverse of the normal cumulative distribution 

Compatibility functions 
Returns the inverse of the normal cumulative distribution 

Statistical functions 
Returns the standard normal cumulative distribution 

Compatibility functions 
Returns the standard normal cumulative distribution 

Statistical functions 
Returns the inverse of the standard normal cumulative distribution 

Compatibility functions 
Returns the inverse of the standard normal cumulative distribution 

Financial functions 
Returns the periodic payment for an annuity 

Financial functions 
Returns the payment on the principal for an investment for a given period 

Statistical functions 
Returns the Poisson distribution 

Compatibility functions 
Returns the Poisson distribution 

Math and trigonometry functions 
Returns a random number between 0 and 1 

Statistical functions 
Estimates standard deviation based on a sample 

Compatibility functions 
Estimates standard deviation based on a sample 

Statistical functions 
Returns the Student's tdistribution 

Compatibility functions 
Returns the Student's tdistribution 

Statistical functions 
Returns the Percentage Points (probability) for the Student tdistribution 

Statistical functions 
Returns the inverse of the Student's tdistribution 

Compatibility functions 
Returns the inverse of the Student's tdistribution 

Statistical functions 
Estimates variance based on a sample 

Compatibility functions 
Estimates variance based on a sample 

Financial functions 
Returns the internal rate of return for a schedule of cash flows that is not necessarily periodic 
Accurate and consistent function names
The following functions have new names that are more consistent with the function definitions of the scientific community and with other function names in Excel. The new function names also more accurately describe their functionality. For example, because the CRITBINOM function returns the inverse of the binomial distribution, BINOM.INV is a more appropriate name for this function.
Some renamed functions, such as BETA.DIST, have an additional parameter so you can specify the type of distribution (lefttail cumulative or probability density).
For backward compatibility with earlier versions of Excel, the functions are still available with their old name in the compatibility functions category. However, if backward compatibility is not required, you should start using the renamed functions instead.
Renamed function 
Function category 
Purpose 
Statistical functions 
Returns the beta cumulative distribution function 

Statistical functions 
Returns the inverse of the cumulative distribution function for a specified beta distribution 

Statistical functions 
Returns the individual term binomial distribution probability 

Statistical functions 
Returns the smallest value for which the cumulative binomial distribution is less than or equal to a criterion value 

Math and trigonometry functions 
Rounds a number to the nearest integer or to the nearest multiple of significance 

Statistical functions 
Returns the cumulative beta probability density function 

Statistical functions 
Returns the onetailed probability of the chisquared distribution 

Statistical functions 
Returns the cumulative beta probability density function 

Statistical functions 
Returns the inverse of the onetailed probability of the chisquared distribution 

Statistical functions 
Returns the test for independence 

Statistical functions 
Returns the confidence interval for a population mean 

Statistical functions 
Returns the confidence interval for a population mean, using a Student's t distribution 

Statistical functions 
Returns covariance, the average of the products of paired deviations 

Statistical functions 
Returns the sample covariance, the average of the products deviations for each data point pair in two data sets 

Engineering functions 
Returns the error function 

Engineering functions 
Returns the complementary ERF function integrated between x and infinity 

Statistical functions 
Returns the exponential distribution 

Statistical functions 
Returns the F probability distribution 

Statistical functions 
Returns the F probability distribution 

Statistical functions 
Returns the inverse of the F probability distribution 

Statistical functions 
Returns the inverse of the F probability distribution 

Statistical functions 
Returns the result of an Ftest 

Math and trigonometry functions 
Rounds a number the nearest integer or to the nearest multiple of significance; regardless of the sign of the number, the number is rounded up 

Statistical functions 
Returns the gamma distribution 

Statistical functions 
Returns the inverse of the gamma cumulative distribution 

Statistical functions 
Returns the natural logarithm of the gamma function, Γ(x) 

Statistical functions 
Returns the hypergeometric distribution 

Math and trigonometry functions 
Returns a number that is rounded up to the nearest integer or to the nearest multiple of significance 

Statistical functions 
Returns the cumulative lognormal distribution 

Statistical functions 
Returns the inverse of the lognormal cumulative distribution 

Statistical functions 
Returns a vertical array of the most frequently occurring, or repetitive values in an array or range of data 

Statistical functions 
Returns the most common value in a data set 

Statistical functions 
Returns the negative binomial distribution 

Date and time functions 
Returns the number of whole workdays between two dates using parameters to indicate which and how many days are weekend days 

Statistical functions 
Returns the normal cumulative distribution 

Statistical functions 
Returns the inverse of the normal cumulative distribution 

Statistical functions 
Returns the standard normal cumulative distribution 

Statistical functions 
Returns the inverse of the standard normal cumulative distribution 

Statistical functions 
Returns the kth percentile of values in a range, where k is in the range 0 to 1, exclusive 

Statistical functions 
Returns the kth percentile of values in a range 

Statistical functions 
Returns the rank of a value in a data set as a percentage (0 to 1, exclusive) of the data set 

Statistical functions 
Returns the percentage rank of a value in a data set 

Statistical functions 
Returns the Poisson distribution 

Statistical functions 
Returns the quartile of the data set, based on percentile values from 0 to 1, exclusive 

Statistical functions 
Returns the quartile of a data set 

Statistical functions 
Returns the rank of a number in a list of numbers 

Statistical functions 
Returns the rank of a number in a list of numbers 

Statistical functions 
Calculates standard deviation based on the entire population 

Statistical functions 
Estimates standard deviation based on a sample 

Statistical functions 
Returns the Percentage Points (probability) for the Student tdistribution 

Statistical functions 
Returns the Percentage Points (probability) for the Student tdistribution 

Statistical functions 
Returns the Student's tdistribution 

Statistical functions 
Returns the tvalue of the Student's tdistribution as a function of the probability and the degrees of freedom 

Statistical functions 
Returns the Student's tdistribution 

Statistical functions 
Returns the probability associated with a Student's ttest 

Statistical functions 
Calculates variance based on the entire population 

Statistical functions 
Estimates variance based on a sample 

Statistical functions 
Returns the Weibull distribution 

Date and time functions 
Returns the serial number of the date before or after a specified number of workdays using parameters to indicate which and how many days are weekend days 

Statistical functions 
Returns the onetailed probabilityvalue of a ztest 
Consistency with best practices
The following functions were added because they are more consistent with best practices than existing functions. For example, the RANK.AVG function is more in line with how statisticians expect the function to work than the existing RANK function.
Renamed function 
Function category 
Purpose 
Statistical functions 
Returns the cumulative beta probability density function 

Statistical functions 
Returns the cumulative beta probability density function 

Statistical functions 
Returns the confidence interval for a population mean, using a Student's t distribution 

Statistical functions 
Returns the sample covariance, the average of the products deviations for each data point pair in two data sets 

Statistical functions 
Returns the exponential distribution 

Statistical functions 
Returns the F probability distribution 

Statistical functions 
Returns the inverse of the F probability distribution 

Statistical functions 
Returns a vertical array of the most frequently occurring, or repetitive values in an array or range of data 

Date and time functions 
Returns the number of whole workdays between two dates using parameters to indicate which and how many days are weekend days 

Statistical functions 
Returns the kth percentile of values in a range, where k is in the range 0 to 1, exclusive 

Statistical functions 
Returns the rank of a value in a data set as a percentage (0 to 1, exclusive) of the data set 

Statistical functions 
Returns the quartile of the data set, based on percentile values from 0 to 1, exclusive 

Statistical functions 
Returns the rank of a number in a list of numbers 

Statistical functions 
Returns the Percentage Points (probability) for the Student tdistribution 

Statistical functions 
Returns the tvalue of the Student's tdistribution as a function of the probability and the degrees of freedom 

Date and time functions 
Returns the serial number of the date before or after a specified number of workdays using parameters to indicate which and how many days are weekend days 
New functions
The following function has been added to the Excel function library. This function can be used in the current version of Excel but is incompatible with Excel 2008 and Excel 972004. If backward compatibility is required, you can run the Compatibility Checker so that you can make the necessary changes in your sheet to avoid errors.
New function 
Function category 
Purpose 
Math and trigonometry functions 
Returns an aggregate in a list or database 
Backward compatibility
To share your sheet with other people who do not have Excel 2011 installed, you can use the compatibility functions instead of the renamed functions. Earlier versions of Excel recognize the old names and provide the expected results.
Selecting the right function in the sheet
When you start entering a function in the sheet, Formula AutoComplete lists both renamed and compatibility functions. The functions are organized by category to make it easier for you to click the one that you want to use. For example, if you type in =beta, Formula AutoComplete displays possible choices under the categories Functions and Compatibility Functions, and also lists any recently used functions that match what you are typing.
Formula AutoComplete
Checking for compatibility issues
New functions (such as AGGREGATE) or functions with algorithm and accuracy improvements (such as BETA.DIST) are incompatible with earlier versions of Excel. Earlier versions of Excel can't recognize the new functions, and #NAME? errors will be displayed instead of the expected results. Before you save your workbook, you can run the Compatibility Report to determine whether new functions were used. Then you can make the necessary changes to avoid errors when the workbook is opened in an earlier version of Excel (Excel 972004 or Excel 2008).
To run the Compatibility Report, do the following:

On the View menu, under Toolbox, click Compatibility Report.

On the Check compatibility with popup menu, click the version of Excel that you want to check for compatibility issues.
The Results window displays a message that explains whether your workbook contains functions that are not available in the version of Excel that you selected.
Compatibility Report