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Simplify log(1/x) into -log(x) (and similarly for log10)

issue#70
Sébastien Villemot 2019-01-28 15:15:58 +01:00
parent 71be51c464
commit c5fc2e38c1
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GPG Key ID: 2CECE9350ECEBE4A
1 changed files with 20 additions and 8 deletions
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28
src/DataTree.cc
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@ -357,29 +357,41 @@ DataTree::AddExp(expr_t iArg1)
expr_t expr_t
DataTree::AddLog(expr_t iArg1) DataTree::AddLog(expr_t iArg1)
{ {
if (iArg1 != Zero && iArg1 != One) if (iArg1 == One)
return AddUnaryOp(UnaryOpcode::log, iArg1);
else if (iArg1 == One)
return Zero; return Zero;
else
if (iArg1 == Zero)
{ {
cerr << "ERROR: log(0) not defined!" << endl; cerr << "ERROR: log(0) not defined!" << endl;
exit(EXIT_FAILURE); exit(EXIT_FAILURE);
} }
// Try to simplify log(1/x) into -log(x)
auto barg1 = dynamic_cast<BinaryOpNode *>(iArg1);
if (barg1 && barg1->op_code == BinaryOpcode::divide && barg1->arg1 == One)
return AddUMinus(AddLog(barg1->arg2));
return AddUnaryOp(UnaryOpcode::log, iArg1);
} }
expr_t expr_t
DataTree::AddLog10(expr_t iArg1) DataTree::AddLog10(expr_t iArg1)
{ {
if (iArg1 != Zero && iArg1 != One) if (iArg1 == One)
return AddUnaryOp(UnaryOpcode::log10, iArg1);
else if (iArg1 == One)
return Zero; return Zero;
else
if (iArg1 == Zero)
{ {
cerr << "ERROR: log10(0) not defined!" << endl; cerr << "ERROR: log10(0) not defined!" << endl;
exit(EXIT_FAILURE); exit(EXIT_FAILURE);
} }
// Try to simplify log10(1/x) into -log10(x)
auto barg1 = dynamic_cast<BinaryOpNode *>(iArg1);
if (barg1 && barg1->op_code == BinaryOpcode::divide && barg1->arg1 == One)
return AddUMinus(AddLog10(barg1->arg2));
return AddUnaryOp(UnaryOpcode::log10, iArg1);
} }
expr_t expr_t