From 3cff2acc8eec95183fe4cd3dcc3a3bf30b37ce66 Mon Sep 17 00:00:00 2001
From: Julian Weigt <juw@posteo.de>
Date: Sun, 28 Dec 2025 15:40:34 +0000
Subject: Add root_to_string function to enable printing of roots.

---
 charf.c        | 5 +++--
 double-error.c | 6 ++++++
 double-error.h | 2 ++
 double.c       | 5 +++++
 double.h       | 2 ++
 ratio.c        | 8 +++++++-
 ratio.h        | 2 ++
 7 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/charf.c b/charf.c
index 6e319ec..670e4d0 100644
--- a/charf.c
+++ b/charf.c
@@ -177,13 +177,14 @@ void compute(EXPTYPE p, int t){
 	/*Print f and ||Mf^{(k)}||_p/||f^{(k)}||_p if the latter is close to 1/2.*/
 	//if(to_double(r)>.4997)
 	if(to_double(r)>.65)
+	//if(to_double(r)>.30)
 	{
 		printf("f: ");
 		for(int i=0;i<D;i++) printf("%1.0f ",to_double(f[i]));
 		printf("\n");
 		char s[128];
-		to_string(s,r);
-		printf("%.4f  (%s)\n",to_double(r),s);
+		root_to_string(s,r,p);
+		printf("%s\n",s);
 	}
 }
 
diff --git a/double-error.c b/double-error.c
index 06d27ae..d5bac3d 100644
--- a/double-error.c
+++ b/double-error.c
@@ -108,3 +108,9 @@ double_error power(double_error de, double_error p) {
 }
 
 double to_double(double_error de){ return de.v; }
+
+bool root_to_string(char* s, double_error de, double_error p){
+	double_error de1p = power(de,ratio(convert_int(1),p));
+	to_string(s,de1p);
+	return true;
+}
diff --git a/double-error.h b/double-error.h
index bce8cd5..23b78d9 100644
--- a/double-error.h
+++ b/double-error.h
@@ -23,3 +23,5 @@ double_error power(double_error,double_error);
 double to_double(double_error);
 
 bool to_string(char*,double_error);
+
+bool root_to_string(char*,double_error,double_error);
diff --git a/double.c b/double.c
index cf4796c..f86a586 100644
--- a/double.c
+++ b/double.c
@@ -31,3 +31,8 @@ bool to_string(char* s, double d){
 	sprintf(s,"%f",d);
 	return true;
 }
+
+bool root_to_string(char* s, double d, double p){
+	to_string(s,pow(d,1/p));
+	return true;
+}
diff --git a/double.h b/double.h
index e0d0a21..98949b1 100644
--- a/double.h
+++ b/double.h
@@ -21,3 +21,5 @@ double power(double,double);
 double to_double(double);
 
 double to_string(char*,double);
+
+double root_to_string(char*,double,double);
diff --git a/ratio.c b/ratio.c
index 07a28ce..3b38ea7 100644
--- a/ratio.c
+++ b/ratio.c
@@ -127,8 +127,14 @@ double to_double(rational r){
 	return i*((double)r.n)/((double)r.d);
 }
 
-bool to_string(char* s,rational r){
+bool to_string(char* s, rational r){
 	double f = to_double(r);
 	sprintf(s,"%llu / %llu = %f +/- %6.1e",r.n,r.d,f,f*DBL_EPSILON);
 	return true;
 }
+
+bool root_to_string(char* s, rational r, unsigned int p){
+	double f = pow(to_double(r),1.0/p);
+	sprintf(s,"(%llu / %llu)^1/%i = %f +/- %6.1e",r.n,r.d,p,f,2*DBL_EPSILON*f);
+	return true;
+}
diff --git a/ratio.h b/ratio.h
index 5899cfa..cd50c8e 100644
--- a/ratio.h
+++ b/ratio.h
@@ -28,3 +28,5 @@ rational power(rational,unsigned int);
 double to_double(rational);
 
 bool to_string(char*,rational r);
+
+bool root_to_string(char*,rational r,unsigned int);
-- 
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