From 932efe1a370e7a8c9f6c7a2dd0beddb36fb7a601 Mon Sep 17 00:00:00 2001
From: Arun Isaac
Date: Fri, 7 May 2021 16:40:54 +0530
Subject: Add rtol? predicate.

* src/utils.sc (rtol?): New function.
* include/utils.h (rtol_p): Declare it.
---
 include/utils.h | 1 +
 src/utils.sc    | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/include/utils.h b/include/utils.h
index 03a8e2e..bc2952c 100644
--- a/include/utils.h
+++ b/include/utils.h
@@ -38,6 +38,7 @@ double gaussian_pdf (double x);
 double gaussian_cdf (double x);
 
 double rerror (double approx, double exact);
+int rtol_p (double approx, double exact, double rtol);
 
 double bisection (gsl_function* f, double a, double b);
 double bisection_rlimit (gsl_function* f, double a, double b);
diff --git a/src/utils.sc b/src/utils.sc
index 20452b0..94b7dcd 100644
--- a/src/utils.sc
+++ b/src/utils.sc
@@ -89,6 +89,11 @@ the range [0,pi]."
 exact value EXACT."
   (return (fabs (- 1 (/ approx exact)))))
 
+(define (rtol? approx exact rtol) (int double double double)
+  "Return 1 if the approximate value APPROX is within RTOL relative
+tolerance of the exact value EXACT. Else, return 0."
+  (return (< (rerror approx exact) rtol)))
+
 (sc-define-syntax (with-root-fsolver solver solver-type function a b body ...)
   (with-alloc solver gsl-root-fsolver*
               (gsl-root-fsolver-alloc solver-type)
-- 
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