diff --git a/README.md b/README.md
index fc86fbb..56cb657 100644
--- a/README.md
+++ b/README.md
@@ -210,7 +210,8 @@ FUNCTION     | NOTES
 [p_acos()](src/math/p_acos.c)         | arc cosine  
 [p_acosh()](src/math/p_acosh.c)       | arc hyperbolic cosine  
 [p_asin()](src/math/p_asin.c)         | arc sine  
-[p_asinh()](src/math/p_asinh.c)       | arc hyperbolic sine  
+[p_asinh()](src/math/p_asinh.c)       | arc hyperbolic sine 
+[p_atan()](src/math/p_atan.c)         | arc tan  
 [p_cbrt()](src/math/p_cbrt.c)         | cubic root                    
 [p_cos()](src/math/p_cos.c)           | cosine  
 [p_cosh()](src/math/p_cosh.c)         | hyperbolic cosine  
diff --git a/src/math/p_atan.c b/src/math/p_atan.c
index a9cc826..4db5e36 100644
--- a/src/math/p_atan.c
+++ b/src/math/p_atan.c
@@ -1,26 +1,6 @@
-#include <pal.h>
-
 /*
- * -1 <= x <= 1
- * atan x = a1 * x + a3 * x^3 + ... + a9 * x^9 + e(x)
- * |e(x)| <= 10^-5
- */
-static inline float _p_atan(const float x)
-{
-    const float a1 =  0.9998660f;
-    const float a3 = -0.3302995f;
-    const float a5 =  0.1801410f;
-    const float a7 = -0.0851330f;
-    const float a9 =  0.0208351f;
-    float x2 = x * x;
-    return x * (a1 + x2 * (a3 + x2 * (a5 + x2 * (a7 + x2 * a9))));
-}
-
-/**
  *
- * Calculates inverse tangent (arc tangent) of the input value. The function
- * returns a value between -pi/2 to pi/2 but does not check for illegal input
- * values.
+ * Calculates inverse tangent (arc tangent). 
  *
  * @param a     Pointer to input vector
  *
@@ -31,11 +11,34 @@ static inline float _p_atan(const float x)
  * @return      None
  *
  */
+
 void p_atan_f32(const float *a, float *c, int n)
 {
+    int i;int sign; float ff; float x;
+    float r,r2,r4,r6,r8;
+    float pi4 = 0.78539816339f;                      // constant=pi/4
+
+    for ( i = 0; i < n; i++)
+      {
+       const float *pa = (a+i);
+             float *pc = (c+i);
+       ff = *pa;
+       if (ff >= 0) sign = 1.0; else sign = -1.0;     // store sign of input variable
+       if (ff < 0) x = ff * (-1.0f); else x = ff;     // this is equivalent of x=abs(a)
+
+       r  = (x-1)/(x+1);
+       r2 = r * r ; r4 = r2*r2 ; r6 = r4*r2 ; r8 = r4*r4 ;
+
+       float z = pi4
+        +    (+0.9999993329f*r
+        +r2 *(-0.3332985605f*r
+        +r  *(+0.1994653599f*r2
+        +    (-0.1390853351f*r4
+        +    (+0.0964200441f*r6
+        +    (-0.0559098861f*r8
+        +r4 *(+0.0218612288f*r6
+        +    (-0.0040540580f*r8))))))));
 
-    int i;
-    for (i = 0; i < n; i++) {
-        c[i] = _p_atan(a[i]);
-    }
+       *pc = sign*z;
+      }
 }
diff --git a/tests/math/gold/p_atan_f32.dat b/tests/math/gold/p_atan_f32.dat
index 01d857f..9ab7942 100644
--- a/tests/math/gold/p_atan_f32.dat
+++ b/tests/math/gold/p_atan_f32.dat
@@ -1,100 +1,100 @@
--0.107358,-0.049577,0.000000,-0.106948
-0.051781,-0.265425,0.000000,0.051735
-0.941475,-0.975603,0.000000,0.755263
--0.770979,-0.360797,0.000000,-0.656793
-0.738044,-0.380252,0.000000,0.635805
-0.608158,-0.123753,0.000000,0.546396
--0.066886,0.380368,0.000000,-0.066787
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-0.968926,0.910675,0.000000,0.769617
--0.207846,-0.573708,0.000000,-0.204928
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-0.682603,0.521601,0.000000,0.598954
--0.536897,0.615399,0.000000,-0.492728
--0.076406,-0.549893,0.000000,-0.076258
--0.683411,0.816236,0.000000,-0.599505
-0.400530,0.368370,0.000000,0.380963
--0.449189,0.342005,0.000000,-0.422179
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-0.981208,0.130812,0.000000,0.775913
-0.399579,0.589365,0.000000,0.380143
--0.992941,-0.667307,0.000000,-0.781856
--0.030266,0.472158,0.000000,-0.030257
-0.542991,-0.061340,0.000000,0.497446
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-0.418914,-0.105983,0.000000,0.396704
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--0.282045,-0.425768,0.000000,-0.274904
--0.354768,-0.274987,0.000000,-0.340916
--0.093074,0.614965,0.000000,-0.092807
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--0.446374,0.580004,0.000000,-0.419834
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--0.571379,0.976033,0.000000,-0.519109
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