MPE/iX Shell and Utilities Reference Manual, Vol 1

bc(1) MPE/iX Shell and Utilities bc(1)

You can use the following functions if –l is speciﬁed on the command line. If it is not, the

function names are not recognized. There are two names for each function: a full name, and a

single character name for compatibility with POSIX.2. The full names are the same as the

equivalent functions in the standard C math library.

atan(expression)or a(expression)

calculates the arctangent of expression, returning an angle in radians.

cos(expression)or c(expression)

calculates the cosine of expression, where expression is an angle in radians.

exp(expression)or e(expression)

calculates the exponential of expression (that is, the value e to the power of expression).

jn(integer,expression)or j(integer,expression)

calculates the Bessel function of expression, with order integer.

log(expression)or l(expression)

calculates the natural logarithm of expression.

sin(expression)or s(expression)

calculates the sine of expression, where expression is an angle in radians.

EXAMPLES

This sections provides some examples of how to use the bc language to accomplish various

things.

Here is a simple function to calculate the sales tax on a purchase. The amount of the purchase

is given by purchase, and the amount of the sales tax (in per cent) is given by tax.

define sales_tax(purchase,tax) {

auto old_scale

scale = 2

tax = purchase*(tax/100)

scale = old_scale

return (tax)

}

For example,

sales_tax(23.99,6)

calculates 6% tax on a purchase of $23.99. The function temporarily sets the scale value to 2

so that the monetary ﬁgures have two ﬁgures after the decimal point. Remember that bc trun-

cates calculations instead of rounding, so some accuracy may be lost. It is better to use one

more digit than needed and perform the rounding at the end. The round2() function, shown

later in this section, rounds a number to two decimal places.

1-60 Commands and Utilities