A.13.3 Between Versions 2 and 3

• 259 new built-in objects have been added, some of whose names may conflict with names already being used.
• N[expr, n] now always tries to give n digits of precision if possible, rather than simply starting with n digits of precision.

• All expressions containing only numeric functions and numerical constants are now converted to approximate numerical form whenever they contain any approximate numbers.
• Many expressions involving exact numbers that used to remain unevaluated are now evaluated. Example: Floor[(7/3)^20].
• Plus and Times now apply built-in rules before user-defined ones, so it is no longer possible to make definitions such as 2+2=5.
• The operator precedence for . and ** has been changed so as to be below ^. This has the consequence that expressions previously written in InputForm as a . b ^ n must now be written as (a . b)^n. V2Get[file] will read a file using old operator precedences.
• \^ is now an operator used to generate a superscript. Raw octal codes must be used instead of \^A for inputting control characters.
• In Mathematica notebooks, several built-in Mathematica functions are now output by default using special characters. Example: x->y is output as xy in StandardForm.
• More sophisticated definite integrals now yield explicit If constructs unless the option setting GenerateConditions->False is used.
• HeldPart[expr, i, j, ... ] has been superseded by Extract[expr, {i, j, ... }, Hold].
• Literal[pattern] has been replaced by HoldPattern[pattern]. Verbatim[pattern] has been introduced. Functions like DownValues return their results wrapped in HoldPattern rather than Literal.
• ReplaceHeldPart[expr, new, pos] has been superseded by ReplacePart[expr, Hold[new], pos, 1].
• ToHeldExpression[expr] has been superseded by ToExpression[expr, form, Hold].
• Trig as an option to algebraic manipulation functions has been superseded by the explicit functions TrigExpand, TrigFactor and TrigReduce.
• AlgebraicRules has been superseded by PolynomialReduce.
• The option LegendreType has been superseded by an additional optional argument to LegendreP and LegendreQ.
• WeierstrassP[u, {, }] now takes and in a list.
• $Letters and $StringOrder now have built-in values only, but these handle all possible Mathematica characters.
• StringByteCount is no longer supported.
• Arbitrary-precision approximate real numbers are now given by default as digits`prec in InputForm. This behavior is controlled by $NumberMarks.
• Large approximate real numbers are now given by default as digits*^exponent in InputForm.
• HomeDirectory[ ] has been replaced by $HomeDirectory.
• Dump has been superseded by DumpSave.
• $PipeSupported and $LinkSupported are now obsolete, since all computer systems support pipes and links.
• LinkOpen has been superseded by LinkCreate, LinkConnect and LinkLaunch.
• Subscripted has been superseded by RowBox, SubscriptBox, etc.
• Subscript and Superscript now represent complete subscripted and superscripted quantities, not just subscripts and superscripts.
• FontForm and DefaultFont have been superseded by StyleForm and TextStyle.

In the notebook front end, changes that were made include:

• The file format for notebooks has been completely changed in order to support new notebook capabilities.
• Notebook files are now by default given .nb rather than .ma extensions; .mb files are now superfluous.
• The front end will automatically ask to convert any old notebook that you tell it to open.
• The kernel command NotebookConvert can be used to convert notebook files from Version 2 to Version 3 format.
• The default format type for input cells is now StandardForm rather than InputForm.
• The organization of style sheets, as well as the settings for some default styles, have been changed.
• Some command key equivalents for menu items have been rearranged.