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C++ Mathematical Expression Library (ExprTk) http://www.partow.net/programming/exprtk/index.html

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Arash Partow 2014-01-23 07:32:55 +11:00
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@ -41,6 +41,8 @@ operations, functions and processes:
(8) Calculus: numerical integration and differentiation (8) Calculus: numerical integration and differentiation
(9) Optimisations: constant-folding and simple strength reduction
[02 - EXAMPLE EXPRESSIONS] [02 - EXAMPLE EXPRESSIONS]
@ -591,39 +593,44 @@ correctly optimize such expressions for a given architecture.
(14) The inbuilt polynomial functions can be at most of degree 12. (14) The inbuilt polynomial functions can be at most of degree 12.
(15) Where appropriate constant folding optimisations will be (15) Where appropriate constant folding optimisations may be
applied. (eg: The expression '2+(3-(x/y))' becomes '5-(x/y)') applied. (eg: The expression '2+(3-(x/y))' becomes '5-(x/y)')
(16) String processing capabilities are available by default. (16) Where applicable strength reduction optimisations may be
applied. The following are example of such optimisations:
(a) '(x / y) / z' --> 'x / (y * z)'
(b) '(x / 3)' --> 'x * (1 / 3)'
(17) String processing capabilities are available by default.
To turn them off, the following needs to be defined at To turn them off, the following needs to be defined at
compile time: exprtk_disable_string_capabilities compile time: exprtk_disable_string_capabilities
(17) Composited functions can call themselves or any other functions (18) Composited functions can call themselves or any other functions
that have been defined prior to their own definition. that have been defined prior to their own definition.
(18) Recursive calls made from within composited functions will have (19) Recursive calls made from within composited functions will have
a stack size bound by the stack of the executing architecture. a stack size bound by the stack of the executing architecture.
(19) The entity relationship between symbol_table and an expression (20) The entity relationship between symbol_table and an expression
is one-to-many. Hence the intended use case is to have a single is one-to-many. Hence the intended use case is to have a single
symbol table manage the variable and function requirements of symbol table manage the variable and function requirements of
multiple expressions. An inappropriate approach would be to have multiple expressions. An inappropriate approach would be to have
a unique symbol table for each unique expression. a unique symbol table for each unique expression.
(20) The common use-case for an expression is to have it compiled (21) The common use-case for an expression is to have it compiled
only once and then subsequently have it evaluated multiple only once and then subsequently have it evaluated multiple
times. An extremely inefficient approach would be to recompile times. An extremely inefficient approach would be to recompile
an expression from its string form every time it requires an expression from its string form every time it requires
evaluating. evaluating.
(21) The following are examples of compliant floating point value (22) The following are examples of compliant floating point value
representations: representations:
(a) 12345 (b) -123.456 (a) 12345 (b) -123.456
(c) +123.456e+12 (d) 123.456E-12 (c) +123.456e+12 (d) 123.456E-12
(e) +012.045e+07 (f) .1234 (e) +012.045e+07 (f) .1234
(g) 123.456f (h) -321.654E+3L (g) 123.456f (h) -321.654E+3L
(22) Expressions may contain any of the following comment styles: (23) Expressions may contain any of the following comment styles:
1. // .... \n 1. // .... \n
2. # .... \n 2. # .... \n
3. /* .... */ 3. /* .... */