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- Evaluator: A programmable expression evaluator
- ==============================================
-
- Evaluator is a small RISC OS-application that evaluates numerical expres-
- sions. It also can handle userdefined functions in this expressions!
-
- It simulates the EVAL-function of BASIC: it is like you are at the BASIC
- prompt evaluating expressions. (In fact the program uses the EVAL-function:
- see below.) The program expects input from the keyboard, for instance the
- numeric keypad. After a Return (or a click on the EXE-button) the result
- will be shown in the window. If you are not satisfied with the expression
- you can edit it: you can place the caret at every position in the expression
- you want.
-
- In an expression are allowed:
-
- Arithmetical operators (see below)
- Variables (see below)
- Decimal constants:
- x or xEn
- (with x a real or integer, n an integer)
- Hexadecimal constants:
- &x
- (with x a hexadecimal number)
- Binary constants:
- %x
- (with x a binary number)
- Functions:
- SIN COS TAN ASN ACS ATN DEG RAD
- SQR LN LOG EXP
- INT ABS SGN
- RND PI
- LEN ASC
- Userdefined functions:
- FNx with x the name of the function
-
- Don't forget the multiplication operator when you use brackets: 2*(3+4)
- instead of 2(3+4).
-
- Numerical expressions give numerical results. Additionally you can assign
- a numerical result to a variable. 26 variables are defined: from a to z.
- Allowed is an assignment-statement like:
- <variable> = <expression>
- From then you can use <variable> in any expression.
-
- For more information about expressions: see the BBC BASIC user guide.
-
- Userdefined functions
- ---------------------
-
- This expression evaluator is programmable! You can program your own
- functions and use them in the expressions. For instance: if you program
- the function FNfac(x) to calculate the faculty of x, you can use this
- function in expressions like:
- FNfac(6)/FNfac(4)
- How do you program userdefined functions? You simply program them in BASIC
- and save the program as UserFN. This library of functions will be loaded
- by the Evaluator-program, when you execute it. A UserFN-library must always
- exist in the same directory as Evaluator is located, otherwise an error will
- result.
-
- Every function which gives a numerical result is allowed. For an expla-
- nation of functions: see the BBC BASIC user guide.
-
- Priority
- --------
-
- The priority of the operators is as follows:
-
- 1 - + unary minus and plus
- SIN etc. functions
- ( ) brackets
- 2 ^ raise to the power
- 3 * / DIV MOD multiplication, division, integer
- division and integer remainder
- 4 + - addition and subtraction
-
- Buttons in window
- -----------------
-
- The meaning of the three buttons in the window of Evaluator is as
- follows:
- C : clears the expression,
- MC : clears the memory, i.e. the 26 variables,
- EXE : executes the expression (same function as Return on the key-
- board).
-
- Examples
- --------
-
- Here are some examples of numerical expressions:
-
- 12+3*4^2
- 12+(3*(4^2))
- 2.1E-3/12
- 4*1024*1024
- (-24+SQR(24^2-4*3*5))/(2*3)
- 12^3
- x=3.56*PI
- x/2
- z=LOG(100)/LN(2)
-
- COS(RAD(45))
- ABS(2*4-5*7)
-
- Number conversion:
-
- &EF
- %1010010
-
- ASCII codes:
-
- ASC("A")
-
-
- Walther Schoonenberg
-
-
- Send comments and suggestions to:
-
- Walther Schoonenberg
- Brouwersgracht 190 C
- 1013 HC Amsterdam
- The Netherlands
-