                                  CALCULATOR               HEP1.HLP

    The  calculator  program  processes  numeric  expressions.   A  numeric
    expression may be a simple numeric constant  or variable or it may be a
    series of  variables and  constants using operators  to form  a numeric
    value.  The value  of the numeric expression is displayed  in the upper
    right  corner of  the  screen.  The  following  are  examples of  valid
    numeric expressions using the HEP calculator:

         3                  7.5                 0.000052

         4.875 * PI         SQR(X*X+Y*Y)        ANG = 360/7

    In the  above examples  there is  an expression  with the  variable PI.
    This is a preassigned variable. (PI = 3.14159...)  Another example uses
    the square root function.   In the last example a value  is assigned to
    the variable  ANG.  Variable names are  made up of letters  and numbers
    with the  first character  always a  letter.  The  maximum length  of a
    variable  name  is 8  characters.   Blanks  are  not allowed  within  a
    variable name or within a numeric  constant. Blanks are allowed between
    the elements of an expression.

    You can use  the cursor left and  the cursor right keys  along with the
    "Ins"  and "Del"  keys  to edit  your input.   Pressing  the "Ins"  key
    latches the insert mode and characters will be inserted just before the
    character at  the cursor  position.  Pressing  the "Ins"  key again  or
    using the  cursor direction keys  will turn  off the insert  mode.  The
    "Del" key will delete the character  at the cursor position.  Once your
    expression is  defined, press  the "Enter" key  to process.   When some
    errors are detected,  the cursor is left  on the expression so  you can
    correct the error and continue.

    At the  bottom of the  screen you will see  that pressing the   "F" key
    while you hold down  the "Alt" key will allow you to see  a list of the
    available functions that may be used with the HEP calculator.  By doing
    the same  with the "Alt"  key and the  "V" key  you can see  the values
    assigned to the current variables.  The  values of some of the variable
    names are set by other programs in HEP such as TRIANGLE.

    The arithmetic operators  perform in the standard  order of precedence.
    The  following is  a list  of the  valid  operators in  order of  their
    hierarchy:

         Operator      Operation              Sample Expression

           ( )         Do operations            (X + Y) / Z
                       inside () first.

           ^ or **     Exponentiation            X ^ Y or X**Y

            -          Negation                  -X

           *  /        Multiply  Divide          X * Y    X / Y

           +  -        Add  Subtract             X + Y    X - Y

    If the  leading character  in an expression  is an  arithmetic operator
    then the expression operates on the  current accumulator value shown in
    the upper right corner.  Example:

         Upper right corner displays:  27.39000000

         Expression entered:           -14.21

         New value displayed:          13.18000000

    You can  see where this  would allow you  to do checkbook  balancing by
    first entering a  balance and the entering "+" values  for deposits and
    "-" values for  checks written.  If you  turn on the printer  using the
    "Alt+P"  keys you  will  get a  printout of  each  transaction and  the
    balance.

    If you  want to  write an expression  where the  first character  is an
    operator, say  a "-",  you may  first set  the accumulator  to zero  by
    entering a zero or by just pressing enter.  You could use () to enclose
    your expression and get the same results.

    You can write  an expression or formula  and save it for  repeated use.
    The following  examples show  how this  is done  using the  formula for
    finding the hypotenuse of a right triangle and converting Fahrenheit to

    Celsius:

       Press "Alt+M"                 To save formula.
       SQR(X*X+Y*Y) <Enter>          Enter formula.
       X = 4.875 <Enter>             Assign variable values.
       Y = 9.4375/PI <Enter>
       Press "Alt+E"                 To execute formula.

                            or

       Press "Alt+M"                 Save formula.
       (ACC-32)*5/9 <Enter>          Using the value in the accumulator.
       72 <Enter>                    Enter value.
       Press "Alt+E"                 To execute.






