diff options
| -rw-r--r-- | arith.c | 22 | ||||
| -rw-r--r-- | txr.1 | 25 |
2 files changed, 47 insertions, 0 deletions
@@ -748,6 +748,26 @@ val abso(val anum) } } +static val signum(val anum) +{ + switch (type(anum)) { + case BGNUM: + return if3(ISNEG(mp(anum)), negone, one); + case FLNUM: + { + double a = anum->fl.n; + return flo(if3(a > 0, 1.0, if3(a < 0, -1.0, 0.0))); + } + case NUM: + { + cnum a = c_num(anum); + return if3(a > 0, one, if3(a < 0, negone, zero)); + } + default: + uw_throwf(error_s, lit("signum: ~s is not a number"), anum, nao); + } +} + val mul(val anum, val bnum) { val self = lit("*"); @@ -3176,6 +3196,8 @@ void arith_init(void) reg_varl(intern(lit("*e*"), user_package), flo(M_E)); reg_varl(intern(lit("%e%"), user_package), flo(M_E)); + reg_fun(intern(lit("signum"), user_package), func_n1(signum)); + reg_fun(intern(lit("bignum-len"), user_package), func_n1(bignum_len)); reg_fun(intern(lit("divides"), user_package), func_n2(divides)); reg_fun(intern(lit("bits"), system_package), func_n1(bits)); @@ -34863,6 +34863,31 @@ is positive, it is returned. If is negative, its additive inverse is returned: a positive number of the same type with exactly the same magnitude. +.coNP Function @ signum +.synb +.mets (signum << number ) +.syne +.desc +The +.code signum +function calculates a representation of the sign of +.meta number +as a numeric value. + +If +.meta number +is an integer, then +.code signum +returns -1 if the integer is negative, 1 if the integer is positive, +or else 0. + +If +.meta number +is a floating-point value then +.code signum +returns -1.0 if the value is negative, 1.0 if the value is positive or +else 0.0. + .coNP Functions @, trunc @, floor @ ceil and @ round .synb .mets (trunc < dividend <> [ divisor ]) |