diff --git a/base/special/fast/abs/README.md b/base/special/fast/abs/README.md
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+* * *
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+## C APIs
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+### Usage
+
+```c
+#include "stdlib/math/base/special/fast/abs.h"
+```
+
+#### stdlib_base_fast_abs( x )
+
+Computes the absolute value of a double-precision floating-point number.
+
+```c
+double y = stdlib_base_fats_abs( -5.0 );
+// returns 5.0
+```
+
+The function accepts the following arguments:
+
+- **x**: `[in] double` input value.
+
+```c
+double stdlib_base_fast_abs( const double x );
+```
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+### Examples
+
+```c
+#include "stdlib/math/base/special/fast/abs.h"
+#include
+
+int main( void ) {
+ const double x[] = { 3.14, -3.14, 0.0, 0.0/0.0 };
+
+ double y;
+ int i;
+ for ( i = 0; i < 4; i++ ) {
+ y = stdlib_base_fast_abs( x[ i ] );
+ printf( "|%lf| = %lf\n", x[ i ], y );
+ }
+}
+```
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