From b2bd95848f389065dba2bb2ae1e0c58ed812b29a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andreas=20M=C3=BCller?= <andreas.mueller@ost.ch>
Date: Sun, 6 Jun 2021 21:40:29 +0200
Subject: add new problem

---
 buch/chapters/020-exponential/code/xxl.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 buch/chapters/020-exponential/code/xxl.c

(limited to 'buch/chapters/020-exponential/code')

diff --git a/buch/chapters/020-exponential/code/xxl.c b/buch/chapters/020-exponential/code/xxl.c
new file mode 100644
index 0000000..2c38ffe
--- /dev/null
+++ b/buch/chapters/020-exponential/code/xxl.c
@@ -0,0 +1,19 @@
+/*
+ * xxl.c -- find solution of x^x = 27
+ *
+ * (c) 2021 Prof Dr Andreas Müller, OST Ostschweizer Fachhochschue
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <gsl/gsl_sf_lambert.h>
+
+int	main(int argc, char *argv[]) {
+	double	b = 27;
+	double	w = gsl_sf_lambert_W0(log(b));
+	printf("W_0(log(27))  = %f\n", w);
+	double	x = exp(w);
+	printf("x             = %f\n", x);
+
+	return EXIT_SUCCESS;
+}
-- 
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