BC(1) UNIX Programmer's Manual BC(1)
NAME
bc - arbitrary-precision arithmetic language
SYNOPSIS
bc [ -c ] [ -l ] [ file ... ]
DESCRIPTION
_B_c is an interactive processor for a language which resem-
bles 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 an arbitrary
precision math library. The syntax for _b_c programs is as
follows; L means letter a-z, E means expression, S means
statement.
Comments
are enclosed in /* and */.
Names
simple variables: L
array elements: L [ E ]
The words `ibase', `obase', and `scale'
Other operands
arbitrarily long numbers with optional sign and
decimal point.
( E )
sqrt ( E )
length ( E ) number of significant decimal digits
scale ( E ) number of digits right of decimal point
L ( E , ... , E )
Operators
+ - * / % ^ (% is remainder; ^ is power)
++ -- (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
define L ( L ,..., L ) {
auto L, ... , L
S; ... S
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BC(1) UNIX Programmer's Manual BC(1)
return ( E )
}
Functions in -l math library
s(x) sine
c(x) cosine
e(x) exponential
l(x) log
a(x) arctangent
j(n,x) Bessel function
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 semi-
colons or newlines may separate statements. Assignment to
_s_c_a_l_e influences the number of digits to be retained on
arithmetic operations in the manner of _d_c(1). Assignments
to _i_b_a_s_e or _o_b_a_s_e set the input and output number radix
respectively.
The same letter may be used as an array, a function, and a
simple variable simultaneously. All variables are global to
the program. `Auto' variables are pushed down during func-
tion calls. 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){
auto a, b, c, i, s
a = 1
b = 1
s = 1
for(i=1; 1==1; i++){
a = a*x
b = b*i
c = a/b
if(c == 0) return(s)
s = s+c
}
}
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.
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BC(1) UNIX Programmer's Manual BC(1)
_B_c is actually a preprocessor for _d_c(1), which it invokes
automatically, unless the -c (compile only) option is
present. In this case the _d_c input is sent to the standard
output instead.
FILES
/usr/share/misc/lib.b mathematical library
dc(1) desk calculator proper
SEE ALSO
dc(1)
L. L. Cherry and R. Morris, _B_C - _A_n _a_r_b_i_t_r_a_r_y _p_r_e_c_i_s_i_o_n
_d_e_s_k-_c_a_l_c_u_l_a_t_o_r _l_a_n_g_u_a_g_e
BUGS
No &&, ||, or ! operators.
_F_o_r statement must have all three E's.
_Q_u_i_t is interpreted when read, not when executed.
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