added program to translate adjancency matrices into graphviz encoding. this is useful to display SOCs; adjusted Makefile accordingly

Makefile

@@ -4,7 +4,7 @@
 
 CFLAGS = -Wall -Ofast
 
-all: SOCgen SOCadmissible
+all: SOCgen SOCadmissible SOCgraphviz
 
 %: src/%.c
 	gcc $(CFLAGS) -o $@ $^

src/SOCgraphviz.c

@@ -0,0 +1,80 @@
+// SPDX-FileCopyrightText: 2023 Ämin Baumeler <amin@indyfac.ch> and Eleftherios-Ermis Tselentis <eleftheriosermis.tselentis@oeaw.ac.at>
+//
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <stdio.h>
+
+int main(int argc, char *argv[]) {
+	// Parse command-line arguments
+	if(argc != 2) {
+		fprintf(stderr, "Usage: %s <filename>\n", argv[0]);
+		fprintf(stderr, "       <filename>     File name with adjacency matrices of simple directed graphs\n");
+		fprintf(stderr, "\n");
+		fprintf(stderr, "[FILE FORMAT]\n");
+		fprintf(stderr, "       Each line in `filename' must contain the adjacency matrix of a simple directed graph in the format\n");
+		fprintf(stderr, "         {{a00,a01,...},{a10,a11,...},...}  where aij=1 if and only if the graph has the edge i -> j\n");
+		fprintf(stderr, "       The file `filename' may contain graphs with different order (number of vertices)\n");
+		fprintf(stderr, "\n");
+		fprintf(stderr, "This program translates to adjacency matrices into the Graphviz format, and prints them to stdout.\n");
+		return -1;
+	}
+
+	// Open file
+	FILE *fp;
+	fp = fopen(argv[1], "r");
+	if(fp == NULL){
+		fprintf(stderr, "ERROR: Could not read graphs from file `%s'.\n", argv[1]);
+		return -1;
+	}
+	// Parse
+	int headprinted = 1;
+	int line = 1;
+	int n = -1;
+	int row = 0;
+	int col = 0;
+	char ch;
+	printf("strict digraph \"File_%s_line_%d\" {", argv[1], line);
+	while(!feof(fp)) {
+		ch = fgetc(fp);
+		switch(ch) {
+			case '{':
+				if(row==0 && col==0 && headprinted==0) {
+					headprinted = 1;
+					printf("strict digraph \"File_%s_line_%d\" {", argv[1], line);
+				}
+				break;
+			case '0':
+			case '1':
+				if(ch=='1')
+					printf("%d->%d;", row,col);
+				col++;
+				break;
+			case '}':
+				if(n==-1)
+					n = col;
+				if(col==n) {
+					row++;
+					col=0;
+				}
+				break;
+			case '\n':
+				printf("}\n");
+				headprinted = 0;
+				line++;
+				row = 0;
+				col = 0;
+				n = -1;
+				break;
+			case ',':
+			case ' ':
+			case 0xffffffff:
+				break;
+			default:
+				fprintf(stderr, "File contains wrongly formatted graph\n");
+				fclose(fp);
+				return -1;	// Format error
+		}
+	}
+	fclose(fp);
+	return 0;
+}