add a fast sqrt function for values in between 0 and 1

1 files changed, 27 insertions, 0 deletions

diff --git a/src/test.c b/src/test.c
index b1e0426..c2b7466 100644
--- a/src/test.c
+++ b/src/test.c
@@ -2100,6 +2100,32 @@ err:
     return 1;
 }
 
+int test_fast_sqrt(char *err)
+{
+    /* Tests that the fast_sqrt() function returns values within 0.1% of sqrt(). */
+    size_t i;
+    double x, result, expected;
+
+    init_genrand(0);
+
+    for (i = 0; i < 100; i++) {
+        x = genrand_real2()*2;
+
+        result = fast_sqrt(x);
+        expected = sqrt(x);
+
+        if (!isclose(result, expected, 0, 1e-3)) {
+            sprintf(err, "fast_sqrt() returned %.5g, but expected %.5g", result, expected);
+            goto err;
+        }
+    }
+
+    return 0;
+
+err:
+    return 1;
+}
+
 struct tests {
     testFunction *test;
     char *name;
@@ -2152,6 +2178,7 @@ struct tests {
     {test_argmin, "test_argmin"},
     {test_electron_get_angular_pdf_norm, "test_electron_get_angular_pdf_norm"},
     {test_fast_acos, "test_fast_acos"},
+    {test_fast_sqrt, "test_fast_sqrt"},
 };
 
 int main(int argc, char **argv)