diff --git a/lib/node_modules/@stdlib/math/base/special/avercos/README.md b/lib/node_modules/@stdlib/math/base/special/avercos/README.md
index eccdd1aa5a5e..761940b270fd 100644
--- a/lib/node_modules/@stdlib/math/base/special/avercos/README.md
+++ b/lib/node_modules/@stdlib/math/base/special/avercos/README.md
@@ -105,6 +105,98 @@ for ( i = 0; i < x.length; i++ ) {
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+## C APIs
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+### Usage
+
+```c
+#include "stdlib/math/base/special/avercos.h"
+```
+
+#### stdlib_base_avercos( x )
+
+Compute the [inverse versed cosine][inverse-versed-cosine] of a double-precision floating-point number (in radians).
+
+```c
+double out = stdlib_base_avercos( -3.141592653589793/2.0 );
+// returns ~2.1783
+```
+
+If `x < -2`, `x > 0`, or `x` is `NaN`, the function returns `NaN`.
+
+```c
+double out = stdlib_base_avercos( -3.141592653589793 );
+// returns NaN
+```
+
+The function accepts the following arguments:
+
+- **x**: `[in] double` input value.
+
+```c
+double stdlib_base_avercos( const double x );
+```
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+### Examples
+
+```c
+#include "stdlib/math/base/special/avercos.h"
+#include
+
+int main( void ) {
+ const double x[] = { -2.5, -2.0, -1.5, -1.0, -0.5, 0.5, 1.0, 1.5, 2.0, 2.5 };
+
+ double v;
+ int i;
+ for ( i = 0; i < 10; i++ ) {
+ v = stdlib_base_avercos( x[ i ] );
+ printf( "avercos(%lf) = %lf\n", x[ i ], v );
+ }
+}
+```
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