dr78: #i91870# PMT accuracy; patch from <regina>

# HG changeset patch
# User Eike Rathke [er] <eike.rathke@oracle.com>
# Date 1291388863 -3600
# Node ID 4ca136c3f3c8eb330664884c2ff79e2027d8e4eb
# Parent  c2bc2890eae42a85c3f16085f9d7867799554839

sc/source/core/tool/interpr2.cxx

@@ -1120,24 +1120,23 @@ void ScInterpreter::ScLIA()
     }
 }
 
-double ScInterpreter::ScGetRmz(double fZins, double fZzr, double fBw,
-                       double fZw, double fF)
+double ScInterpreter::ScGetRmz(double fRate, double fNper, double fPv,
+                       double fFv, double fPaytype)
 {
     RTL_LOGFILE_CONTEXT_AUTHOR( aLogger, "sc", "er", "ScInterpreter::ScGetRmz" );
-    double fRmz;
-    if (fZins == 0.0)
-        fRmz = (fBw + fZw) / fZzr;
+    double fPayment;
+    if (fRate == 0.0)
+        fPayment = (fPv + fFv) / fNper;
     else
     {
-        double fTerm = pow(1.0 + fZins, fZzr);
-        if (fF > 0.0)
-            fRmz = (fZw * fZins / (fTerm - 1.0)
-                        + fBw * fZins / (1.0 - 1.0 / fTerm)) / (1.0+fZins);
-        else
-            fRmz = fZw * fZins / (fTerm - 1.0)
-                        + fBw * fZins / (1.0 - 1.0 / fTerm);
+        if (fPaytype > 0.0) // payment in advance
+            fPayment = (fFv + fPv * exp( fNper * ::rtl::math::log1p(fRate) ) ) * fRate /
+                (::rtl::math::expm1( (fNper + 1) * ::rtl::math::log1p(fRate) ) - fRate);
+        else  // payment in arrear
+            fPayment = (fFv + fPv * exp(fNper * ::rtl::math::log1p(fRate) ) ) * fRate /
+                ::rtl::math::expm1( fNper * ::rtl::math::log1p(fRate) );
     }
-    return -fRmz;
+    return -fPayment;
 }
 
 void ScInterpreter::ScRMZ()