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

This commit is contained in:
Arash Partow 2016-10-04 10:27:29 +11:00
parent c165d4864e
commit 3bd10f1ba6
2 changed files with 31 additions and 31 deletions
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32
exprtk_simple_example_10.cpp
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@ -44,22 +44,22 @@ void newton_sqrt()
.add( .add(
function_t( // define function: newton_sqrt(x) function_t( // define function: newton_sqrt(x)
"newton_sqrt", "newton_sqrt",
" switch " " switch "
" { " " { "
" case x < 0 : -inf; " " case x < 0 : -inf; "
" case x == 0 : 0; " " case x == 0 : 0; "
" case x == 1 : 1; " " case x == 1 : 1; "
" default: " " default: "
" ~{ " " ~{ "
" var z := 100; " " var z := 100; "
" var y := x / 2; " " var sqrt_x := x / 2; "
" repeat " " repeat "
" y := (1 / 2) * (y + (x / y)); " " sqrt_x := (1 / 2) * (sqrt_x + (x / sqrt_x)); "
" if (equal(y * y, x)) " " if (equal(sqrt_x^2, x)) "
" break[y]; " " break[sqrt_x]; "
" until ((z -= 1) <= 0); " " until ((z -= 1) <= 0); "
" }; " " }; "
" } ", " } ",
"x")); "x"));
std::string expression_str = "newton_sqrt(x)"; std::string expression_str = "newton_sqrt(x)";

30
readme.txt
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@ -877,8 +877,8 @@ behaviours when using the expressions in various contexts such as
muli-threading et al. muli-threading et al.
The prescribed method for cloning an expression is to compile it from The prescribed method for cloning an expression is to compile it from
its string form. Doing so will allow the one to properly consider the its string form. Doing so will allow the 'user' to properly consider
exact source of user defined variables and functions. the exact source of user defined variables and functions.
Note: The exprtk::parser is a non-copyable and non-thread safe Note: The exprtk::parser is a non-copyable and non-thread safe
component, and should only be shared via either a reference, a shared component, and should only be shared via either a reference, a shared
@ -893,19 +893,19 @@ operations for compiling multiple expressions via the parser and
inserting the newly minted exprtk::expression instances into a inserting the newly minted exprtk::expression instances into a
std::vector. std::vector.
+----[exprtk::parser]---+
+--[exprtk::parser]--+ | Expression Factory |
| expression factory | | parser_t::compile(...)|
+---->- compile(....) ->---+ +--> ~.~.~.~.~.~.~.~.~.~ ->--+
| +--------------------+ | | +-----------------------+ |
Expressions | | Expressions as Expressions in | | Expressions as
in string form A V exprtk::expression string form A V exprtk::expression
| | instances | | instances
[s0:'x+1']------+ | | +-[e0: x+1] [s0:'x+1']--->--+ | | +-[e0: x+1]
| | | | | | | |
[s1:'2z+y']-----+--+ +-->+-[e1: 2z+y] [s1:'2z+y']-->--+--+ +->+-[e1: 2z+y]
| | | |
[s2:'sin(k+w)']-+ +-[e2: sin(k+w)] [s2:'sin(k+w)']-+ +-[e2: sin(k+w)]
const std::string expression_str[3] const std::string expression_str[3]