Utilities

 

• LVAR: returns the list of global names of an algebraic. The list is sorted by reverse alphabetic order. Square roots are at the beginning. Example:
  'SIN(A)+B*X+1' -> { X B 'SIN(A)' }
• EXEC:
  • doall function:
    if stack 1 is a program executes program at stack level 1 recursively on the components of a list object at stack level 2. Example: { 1 2 3 } << NEG >> EXEC
    is the same as { 1 2 3 } CHS
  • one algebraic substitution:
    If stack 1 is an equation ('objA=objB'), replace objA by objB in stack2.
  • many subsitutions:
    If stack 1 and 2 are lists, replace each object of list2 in stack level 3 by the corresponding object of list1. Example:
    

    'COS(X)+i*SIN(X)' 
    { SIN COS }
    { << i * EXP DUP INV - i 2 * / >>
      << i * EXP DUP INV + 2 / >>
    }

    replace and by complex exponentials. If you call EXPA after you get e^ix.