diff -r 736a341e604b -r eba5aa390aca lemon/clp.cc
--- a/lemon/clp.cc	Thu Jan 21 08:36:53 2021 +0100
+++ b/lemon/clp.cc	Thu Jan 21 18:58:37 2021 +0100
@@ -227,14 +227,14 @@
   }
 
   ClpLp::Value ClpLp::_getCoeff(int ix, int jx) const {
-    CoinBigIndex begin = _prob->clpMatrix()->getVectorStarts()[ix];
-    CoinBigIndex end = begin + _prob->clpMatrix()->getVectorLengths()[ix];
+    CoinBigIndex begin = _prob->clpMatrix()->getVectorStarts()[jx];
+    CoinBigIndex end = begin + _prob->clpMatrix()->getVectorLengths()[jx];
 
     const int* indices = _prob->clpMatrix()->getIndices();
     const double* elements = _prob->clpMatrix()->getElements();
 
-    const int* it = std::lower_bound(indices + begin, indices + end, jx);
-    if (it != indices + end && *it == jx) {
+    const int* it = std::lower_bound(indices + begin, indices + end, ix);
+    if (it != indices + end && *it == ix) {
       return elements[it - indices];
     } else {
       return 0.0;
@@ -461,4 +461,14 @@
     }
   }
 
+   void ClpLp::_write(std::string file, std::string format) const
+  {
+    if(format == "LP")
+      _prob->writeLp(file.c_str(), "", 1e-5, 10, 5,
+                     sense()==ClpLp::MIN?1:-1,
+                     true
+                     );
+    else throw UnsupportedFormatError(format);
+  }
+ 
 } //END OF NAMESPACE LEMON