Use the Simplify > Subexpression Substitution command or press Ctrl+T to substitute a replacement value for one or all occurrences of the highlighted subexpression in an expression.  This command displays a dialog box for entering the replacement subexpression (see Entering Mathematical ExpressionsEntering_Mathematical_Expressions).


The dialog box includes radio buttons for selecting between replacing just the One highlighted subexpression or replacing All occurrences of the subexpression in the expression.  Replacing just the One highlighted subexpression with a new value is a convenient way to edit large expressions.


When satisfied with the replacement subexpression, click on the OK button or press the Enter key to make the substitution(s) and add the result as the last expression in the active algebra window.  Click on the Simplify button or press Alt+S to simplify the result before adding it as the last expression in the active algebra window.  Click on the Cancel button or press the Esc key to abort the command.


You can also use the SUBST function to substitute values for subexpressions of an expression, serially or in parallel.   See the Simplify > Variable Substitution commandGP2.L1 for details.


Note that when substituting a value for a subexpression, only exact matches are replaced.  For example, substitution for x^2 does not also replace occurrences of x^4.  Therefore,

SUBST(a·x^4 + b·x^3 + c·x^2 + d·x + e, x^2, y)

simplifies to

   4      3                 
a·x  + b·x  + d·x + c·y + e 


Other Simplify commandsSimplify_commands 

Created with the Personal Edition of HelpNDoc: Write EPub books for the iPad