Java Utililty Methods atan

double atan(double a)
Returns the arc tangent of an angle, in the range of -pi/2 through pi/2.

return Math.atan(a);

double atan(double a)
Returns the arc tangent of an angle, in the range of -pi/2 through pi/2.

double w, s1, s2, z;
int id;
long hx = Double.doubleToLongBits(a);
long ix = hx & no_sign_mask;
if (ix >= 0x4410000000000000L) {
 if (ix > exp_mask) {
 return (a + a);
 if (hx > 0)
 return (atanhi[3] + atanlo[3]);
 else
 return (-atanhi[3] - atanlo[3]);
if (ix < 0x3fdc000000000000L) {
 if (ix < 0x3e20000000000000L) {
 return (a);
 id = -1;
} else {
 a = Math.abs(a);
 if (ix < 0x3ff3000000000000L) {
 if (ix < 0x3fe6000000000000L) {
 id = 0;
 a = (2.0 * a - 1.0) / (2.0 + a);
 else {
 id = 1;
 a = (a - 1.0) / (a + 1.0);
 } else {
 if (ix < 0x4003800000000000L) {
 id = 2;
 a = (a - 1.5) / (1.0 + 1.5 * a);
 } else {
 id = 3;
 a = -1.0 / a;
z = a * a;
w = z * z;
s1 = z * (aT[0] + w * (aT[2] + w * (aT[4] + w * (aT[6] + w * (aT[8] + w * aT[10])))));
s2 = w * (aT[1] + w * (aT[3] + w * (aT[5] + w * (aT[7] + w * aT[9]))));
if (id < 0)
 return (a - a * (s1 + s2));
else {
 z = atanhi[id] - ((a * (s1 + s2) - atanlo[id]) - a);
 if (hx < 0)
 return (-z);
 else
 return (z);

double atan(double arg)
atan

if (arg > 0) {
 return msatan(arg);
return -msatan(-arg);

double atan(double x)
Approximates the atan function.

double res;
if (Math.abs(x) < 1) {
 res = x / (1 + 0.28 * x * x);
} else {
 if (x < 0.0) {
 x = -x;
 res = (Math.PI / 2 - x / (x * x + 0.28));
 res = -res;
...

float atan(float tan_value)
atan

if (tan_value < -32f) {
 return -1.54f;
} else if (tan_value > 32f) {
 return 1.54f;
} else {
 return atan_table[(int) ((tan_value + 32f) * accuracy_level / 64f)];

float atan(float value)
atan

return (float) Math.atan(value);

float atan(float x)
Arctan

boolean signChange = false;
boolean Invert = false;
int sp = 0;
float x2, a;
if (x < 0.) {
 x = -x;
 signChange = true;
if (x > 1.) {
 x = 1 / x;
 Invert = true;
while (x > (float) Math.PI / 12) {
 sp++;
 a = x + SQRT3;
 a = 1 / a;
 x = x * SQRT3;
 x = x - 1;
 x = x * a;
x2 = x * x;
a = x2 + 1.4087812f;
a = 0.55913709f / a;
a = a + 0.60310579f;
a = a - (x2 * 0.05160454f);
a = a * x;
while (sp > 0) {
 a = a + (float) Math.PI / 6;
 sp--;
if (Invert)
 a = (float) Math.PI / 2 - a;
if (signChange)
 a = -a;
return a;

int atan(int f)
atan

int sqr = mul(f, f);
int result = 1365;
result = mul(result, sqr);
result -= 5579;
result = mul(result, sqr);
result += 11805;
result = mul(result, sqr);
result -= 21646;
...

double atan(Integer a)
Atan.

return Math.atan(a.doubleValue());

double atan(Number x)
atan

return Math.atan(x.doubleValue());