\-l オプション(bc -l)で、標準的な数学関数が使えるようになる
s (x) The sine of x, x is in radians.~ c (x) The cosine of x, x is in radians.~ a (x) The arctangent of x, arctangent returns radians.~ l (x) The natural logarithm of x.~ e (x) The exponential function of raising e to the value x.~ j (n,x) The bessel function of integer order n of x.~
例1) log_2 (x)
define lg(x) { return (l(x) / l(2)); }
例2) 二点間の距離
define dist (x,y,z,u,v,w) { return sqrt((x-u)*(x-u)+(y-v)*(y-v)+(z-w)*(z-w)); }
例3) 羃乗
define pow (x,y) { auto k, ans; ans=1; for ( k=0; k<y; k++ ) { ans = ans*x; } return ans; }