GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
Unix |
Unix v6 |
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bc(1) |
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bc arbitrary precision interactive language [ ] [ file
... ] is an interactive processor for a language which
resembles C but provides unlimited precision arithmetic. It
takes input from any files given, then reads the standard
input. The ‘−l’ argument stands for the
name of a library of mathematical subroutines which contains
sine (named ‘s’), cosine (‘c’),
arctangent (‘a’), natural logarithm
(‘l’), and exponential (‘e’). The
syntax for programs is as follows; E means expression, S
means statement. Comments
are enclosed in /* and */. Names
letters a−z
array elements: letter[E]
The words ‘ibase’, ‘obase’, and
‘scale’ Other operands
arbitrarily long numbers with optional sign and decimal
point.
( E )
sqrt ( E )
<letter> ( E , ... , E ) Operators
+ − * / % ^
++ −− (prefix and postfix; apply to names)
== <= >= != < >
= =+ =− =* =/ =% =^
Statements
E
{ S ; ... ; S }
if ( E ) S
while ( E ) S
for ( E ; E ; E ) S
null statement
break
quit Function definitions are exemplified by
define <letter> ( <letter> ,..., <letter>
) {
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auto <letter>, ... , <letter> |
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S; ... S |
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return ( E ) |
} All function arguments are passed by value. The value
of a statement that is an expression is printed unless the
main operator is an assignment. Either semicolons or
newlines may separate statements. Assignment to influences
the number of digits to be retained on arithmetic
operations. Assignments to or set the input and output
number radix respectively. The same letter may be used as an
array name, a function name, and a simple variable
simultaneously. ‘Auto’ variables are saved and
restored during function calls. All other variables are
global to the program. When using arrays as function
arguments or defining them as automatic variables empty
square brackets must follow the array name. For example
scale = 20
define e(x){
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auto a, b, c, i, s |
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a = 1 |
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b = 1 |
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s = 1 |
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for(i=1; 1==1; i++){ |
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a = a*x |
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b = b*i |
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c = a/b |
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if(c == 0) return(s) |
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s = s+c |
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} |
}
defines a function to compute an approximate value of the
exponential function and
for(i=1; i<=10; i++) e(i)
prints approximate values of the exponential function of the
first ten integers. /usr/lib/lib.b mathematical library (I),
C Reference Manual, ‘‘BC − An Arbitrary
Precision Desk-Calculator Language.’’ No
&&, | | yet.
statement must have all three E’s
is interpreted when read, not when executed.
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bc(1) | |