rust/src/libcore/float.rs

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/*
Module: float
*/
// Currently this module supports from -lm
// C95 + log2 + log1p + trunc + round + rint
export t;
export consts;
export
acos, asin, atan, atan2, ceil, cos, cosh, exp, abs, floor, fmod, frexp,
ldexp, ln, ln1p, log10, log2, modf, rint, round, pow, sin, sinh, sqrt,
tan, tanh, trunc;
export to_str_common, to_str_exact, to_str, from_str;
export lt, le, eq, ne, gt, eq;
export NaN, isNaN, infinity, neg_infinity;
export pow_uint_to_uint_as_float;
export min, max;
export add, sub, mul, div;
export positive, negative, nonpositive, nonnegative;
import mtypes::m_float;
import ctypes::c_int;
import ptr;
// PORT This must match in width according to architecture
import f64;
import m_float = f64;
type t = m_float;
/**
* Section: String Conversions
*/
/*
Function: to_str_common
Converts a float to a string
Parameters:
num - The float value
digits - The number of significant digits
exact - Whether to enforce the exact number of significant digits
*/
fn to_str_common(num: float, digits: uint, exact: bool) -> str {
let (num, accum) = num < 0.0 ? (-num, "-") : (num, "");
let trunc = num as uint;
let frac = num - (trunc as float);
accum += uint::str(trunc);
if frac == 0.0 || digits == 0u { ret accum; }
accum += ".";
let i = digits;
let epsilon = 1. / pow_uint_to_uint_as_float(10u, i);
while i > 0u && (frac >= epsilon || exact) {
frac *= 10.0;
epsilon *= 10.0;
let digit = frac as uint;
accum += uint::str(digit);
frac -= digit as float;
i -= 1u;
}
ret accum;
}
/*
Function: to_str
Converts a float to a string with exactly the number of provided significant
digits
Parameters:
num - The float value
digits - The number of significant digits
*/
fn to_str_exact(num: float, digits: uint) -> str {
to_str_common(num, digits, true)
}
/*
Function: to_str
Converts a float to a string with a maximum number of significant digits
Parameters:
num - The float value
digits - The number of significant digits
*/
fn to_str(num: float, digits: uint) -> str {
to_str_common(num, digits, false)
}
/*
Function: from_str
Convert a string to a float
This function accepts strings such as
* "3.14"
* "+3.14", equivalent to "3.14"
* "-3.14"
* "2.5E10", or equivalently, "2.5e10"
* "2.5E-10"
* "", or, equivalently, "." (understood as 0)
* "5."
* ".5", or, equivalently, "0.5"
Leading and trailing whitespace are ignored.
Parameters:
num - A string, possibly empty.
Returns:
<NaN> If the string did not represent a valid number.
Otherwise, the floating-point number represented [num].
*/
fn from_str(num: str) -> float {
let num = str::trim(num);
let pos = 0u; //Current byte position in the string.
//Used to walk the string in O(n).
let len = str::byte_len(num); //Length of the string, in bytes.
if len == 0u { ret 0.; }
let total = 0f; //Accumulated result
let c = 'z'; //Latest char.
//The string must start with one of the following characters.
alt str::char_at(num, 0u) {
'-' | '+' | '0' to '9' | '.' {}
_ { ret NaN; }
}
//Determine if first char is '-'/'+'. Set [pos] and [neg] accordingly.
let neg = false; //Sign of the result
alt str::char_at(num, 0u) {
'-' {
neg = true;
pos = 1u;
}
'+' {
pos = 1u;
}
_ {}
}
//Examine the following chars until '.', 'e', 'E'
while(pos < len) {
let char_range = str::char_range_at(num, pos);
c = char_range.ch;
pos = char_range.next;
alt c {
'0' to '9' {
total = total * 10f;
total += ((c as int) - ('0' as int)) as float;
}
'.' | 'e' | 'E' {
break;
}
_ {
ret NaN;
}
}
}
if c == '.' {//Examine decimal part
let decimal = 1f;
while(pos < len) {
let char_range = str::char_range_at(num, pos);
c = char_range.ch;
pos = char_range.next;
alt c {
'0' | '1' | '2' | '3' | '4' | '5' | '6'| '7' | '8' | '9' {
decimal /= 10f;
total += (((c as int) - ('0' as int)) as float)*decimal;
}
'e' | 'E' {
break;
}
_ {
ret NaN;
}
}
}
}
if (c == 'e') | (c == 'E') {//Examine exponent
let exponent = 0u;
let neg_exponent = false;
if(pos < len) {
let char_range = str::char_range_at(num, pos);
c = char_range.ch;
alt c {
'+' {
pos = char_range.next;
}
'-' {
pos = char_range.next;
neg_exponent = true;
}
_ {}
}
while(pos < len) {
let char_range = str::char_range_at(num, pos);
c = char_range.ch;
alt c {
'0' | '1' | '2' | '3' | '4' | '5' | '6'| '7' | '8' | '9' {
exponent *= 10u;
exponent += ((c as uint) - ('0' as uint));
}
_ {
break;
}
}
pos = char_range.next;
}
let multiplier = pow_uint_to_uint_as_float(10u, exponent);
//Note: not [int::pow], otherwise, we'll quickly
//end up with a nice overflow
if neg_exponent {
total = total / multiplier;
} else {
total = total * multiplier;
}
} else {
ret NaN;
}
}
if(pos < len) {
ret NaN;
} else {
if(neg) {
total *= -1f;
}
ret total;
}
}
/**
* Section: Arithmetics
*/
/*
Function: pow_uint_to_uint_as_float
Compute the exponentiation of an integer by another integer as a float.
Parameters:
x - The base.
pow - The exponent.
Returns:
<NaN> of both `x` and `pow` are `0u`, otherwise `x^pow`.
*/
fn pow_uint_to_uint_as_float(x: uint, pow: uint) -> float {
if x == 0u {
if pow == 0u {
ret NaN;
}
ret 0.;
}
let my_pow = pow;
let total = 1f;
let multiplier = x as float;
while (my_pow > 0u) {
if my_pow % 2u == 1u {
total = total * multiplier;
}
my_pow /= 2u;
multiplier *= multiplier;
}
ret total;
}
/* Const: NaN */
const NaN: float = 0./0.;
/* Const: infinity */
const infinity: float = 1./0.;
/* Const: neg_infinity */
const neg_infinity: float = -1./0.;
/* Predicate: isNaN */
pure fn isNaN(f: float) -> bool { f != f }
/* Function: add */
pure fn add(x: float, y: float) -> float { ret x + y; }
/* Function: sub */
pure fn sub(x: float, y: float) -> float { ret x - y; }
/* Function: mul */
pure fn mul(x: float, y: float) -> float { ret x * y; }
/* Function: div */
pure fn div(x: float, y: float) -> float { ret x / y; }
/* Function: rem */
pure fn rem(x: float, y: float) -> float { ret x % y; }
/* Predicate: lt */
pure fn lt(x: float, y: float) -> bool { ret x < y; }
/* Predicate: le */
pure fn le(x: float, y: float) -> bool { ret x <= y; }
/* Predicate: eq */
pure fn eq(x: float, y: float) -> bool { ret x == y; }
/* Predicate: ne */
pure fn ne(x: float, y: float) -> bool { ret x != y; }
/* Predicate: ge */
pure fn ge(x: float, y: float) -> bool { ret x >= y; }
/* Predicate: gt */
pure fn gt(x: float, y: float) -> bool { ret x > y; }
/*
Predicate: positive
Returns true if `x` is a positive number, including +0.0 and +Infinity.
*/
pure fn positive(x: float) -> bool { ret x > 0. || (1./x) == infinity; }
/*
Predicate: negative
Returns true if `x` is a negative number, including -0.0 and -Infinity.
*/
pure fn negative(x: float) -> bool { ret x < 0. || (1./x) == neg_infinity; }
/*
Predicate: nonpositive
Returns true if `x` is a negative number, including -0.0 and -Infinity.
(This is the same as `float::negative`.)
*/
pure fn nonpositive(x: float) -> bool {
ret x < 0. || (1./x) == neg_infinity;
}
/*
Predicate: nonnegative
Returns true if `x` is a positive number, including +0.0 and +Infinity.
(This is the same as `float::positive`.)
*/
pure fn nonnegative(x: float) -> bool {
ret x > 0. || (1./x) == infinity;
}
/*
Module: consts
*/
mod consts {
/*
Const: pi
Archimedes' constant
*/
const pi: float = 3.14159265358979323846264338327950288;
/*
Const: frac_pi_2
pi/2.0
*/
const frac_pi_2: float = 1.57079632679489661923132169163975144;
/*
Const: frac_pi_4
pi/4.0
*/
const frac_pi_4: float = 0.785398163397448309615660845819875721;
/*
Const: frac_1_pi
1.0/pi
*/
const frac_1_pi: float = 0.318309886183790671537767526745028724;
/*
Const: frac_2_pi
2.0/pi
*/
const frac_2_pi: float = 0.636619772367581343075535053490057448;
/*
Const: frac_2_sqrtpi
2.0/sqrt(pi)
*/
const frac_2_sqrtpi: float = 1.12837916709551257389615890312154517;
/*
Const: sqrt2
sqrt(2.0)
*/
const sqrt2: float = 1.41421356237309504880168872420969808;
/*
Const: frac_1_sqrt2
1.0/sqrt(2.0)
*/
const frac_1_sqrt2: float = 0.707106781186547524400844362104849039;
/*
Const: e
Euler's number
*/
const e: float = 2.71828182845904523536028747135266250;
/*
Const: log2_e
log2(e)
*/
const log2_e: float = 1.44269504088896340735992468100189214;
/*
Const: log10_e
log10(e)
*/
const log10_e: float = 0.434294481903251827651128918916605082;
/*
Const: ln_2
ln(2.0)
*/
const ln_2: float = 0.693147180559945309417232121458176568;
/*
Const: ln_10
ln(10.0)
*/
const ln_10: float = 2.30258509299404568401799145468436421;
}
// FIXME min/max type specialize via libm when overloading works
// (in theory fmax/fmin, fmaxf, fminf /should/ be faster)
/*
Function: min
Returns the minimum of two values
*/
pure fn min<copy T>(x: T, y: T) -> T { x < y ? x : y }
/*
Function: max
Returns the maximum of two values
*/
pure fn max<copy T>(x: T, y: T) -> T { x < y ? y : x }
/*
Function: acos
Returns the arccosine of an angle (measured in rad)
*/
pure fn acos(x: float) -> float
{ ret m_float::acos(x as m_float) as float }
/*
Function: asin
Returns the arcsine of an angle (measured in rad)
*/
pure fn asin(x: float) -> float
{ ret m_float::asin(x as m_float) as float }
/*
Function: atan
Returns the arctangents of an angle (measured in rad)
*/
pure fn atan(x: float) -> float
{ ret m_float::atan(x as m_float) as float }
/*
Function: atan2
Returns the arctangent of an angle (measured in rad)
*/
pure fn atan2(y: float, x: float) -> float
{ ret m_float::atan2(y as m_float, x as m_float) as float }
/*
Function: ceil
Returns the smallest integral value less than or equal to `n`
*/
pure fn ceil(n: float) -> float
{ ret m_float::ceil(n as m_float) as float }
/*
Function: cos
Returns the cosine of an angle `x` (measured in rad)
*/
pure fn cos(x: float) -> float
{ ret m_float::cos(x as m_float) as float }
/*
Function: cosh
Returns the hyperbolic cosine of `x`
*/
pure fn cosh(x: float) -> float
{ ret m_float::cosh(x as m_float) as float }
/*
Function: exp
Returns `consts::e` to the power of `n*
*/
pure fn exp(n: float) -> float
{ ret m_float::exp(n as m_float) as float }
/*
Function: abs
Returns the absolute value of `n`
*/
pure fn abs(n: float) -> float
{ ret m_float::abs(n as m_float) as float }
/*
Function: floor
Returns the largest integral value less than or equal to `n`
*/
pure fn floor(n: float) -> float
{ ret m_float::floor(n as m_float) as float }
/*
Function: fmod
Returns the floating-point remainder of `x/y`
*/
pure fn fmod(x: float, y: float) -> float
{ ret m_float::fmod(x as m_float, y as m_float) as float }
/*
Function: ln
Returns the natural logaritm of `n`
*/
pure fn ln(n: float) -> float
{ ret m_float::ln(n as m_float) as float }
/*
Function: ldexp
Returns `x` multiplied by 2 to the power of `n`
*/
pure fn ldexp(n: float, i: int) -> float
{ ret m_float::ldexp(n as m_float, i as c_int) as float }
/*
Function: ln1p
Returns the natural logarithm of `1+n` accurately,
even for very small values of `n`
*/
pure fn ln1p(n: float) -> float
{ ret m_float::ln1p(n as m_float) as float }
/*
Function: log10
Returns the logarithm to base 10 of `n`
*/
pure fn log10(n: float) -> float
{ ret m_float::log10(n as m_float) as float }
/*
Function: log2
Returns the logarithm to base 2 of `n`
*/
pure fn log2(n: float) -> float
{ ret m_float::log2(n as m_float) as float }
/*
Function: modf
Breaks `n` into integral and fractional parts such that both
have the same sign as `n`
The integral part is stored in `iptr`.
Returns:
The fractional part of `n`
*/
#[no(warn_trivial_casts)] // FIXME Implement
pure fn modf(n: float, &iptr: float) -> float { unsafe {
ret m_float::modf(n as m_float, ptr::addr_of(iptr) as *m_float) as float
} }
/*
Function: frexp
Breaks `n` into a normalized fraction and an integral power of 2
The inegral part is stored in iptr.
The functions return a number x such that x has a magnitude in the interval
[1/2, 1) or 0, and `n == x*(2 to the power of exp)`.
Returns:
The fractional part of `n`
*/
pure fn frexp(n: float, &exp: c_int) -> float
{ ret m_float::frexp(n as m_float, exp) as float }
/*
Function: pow
*/
pure fn pow(v: float, e: float) -> float
{ ret m_float::pow(v as m_float, e as m_float) as float }
/*
Function: rint
Returns the integral value nearest to `x` (according to the
prevailing rounding mode) in floating-point format
*/
pure fn rint(x: float) -> float
{ ret m_float::rint(x as m_float) as float }
/*
Function: round
Return the integral value nearest to `x` rounding half-way
cases away from zero, regardless of the current rounding direction.
*/
pure fn round(x: float) -> float
{ ret m_float::round(x as m_float) as float }
/*
Function: sin
Returns the sine of an angle `x` (measured in rad)
*/
pure fn sin(x: float) -> float
{ ret m_float::sin(x as m_float) as float }
/*
Function: sinh
Returns the hyperbolic sine of an angle `x` (measured in rad)
*/
pure fn sinh(x: float) -> float
{ ret m_float::sinh(x as m_float) as float }
/*
Function: sqrt
Returns the square root of `x`
*/
pure fn sqrt(x: float) -> float
{ ret m_float::sqrt(x as m_float) as float }
/*
Function: tan
Returns the tangent of an angle `x` (measured in rad)
*/
pure fn tan(x: float) -> float
{ ret m_float::tan(x as m_float) as float }
/*
Function: tanh
Returns the hyperbolic tangent of an angle `x` (measured in rad)
*/
pure fn tanh(x: float) -> float
{ ret m_float::tanh(x as m_float) as float }
/*
Function: trunc
Returns the integral value nearest to but no larger in magnitude than `x`
*/
pure fn trunc(x: float) -> float
{ ret m_float::trunc(x as m_float) as float }
//
// Local Variables:
// mode: rust
// fill-column: 78;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// End:
//