[GiNaC-list] arithmetic error on concat two expressions
Kraus Philipp
philipp.kraus at flashpixx.de
Fri Aug 6 12:03:11 CEST 2010
Hi,
I'm new at GiNaC and I use the lib for create a gradient descent
algorithm (symbolic calculating).
I have a formula "a*x^3+b*y^4" and I subsitute the formula in the
error function "0.5*(t - <formula>)^2".
After the substitution GiNaC returns the expression
"(0.5)*(a*x^3+b*y^4-t)^2".
I use this code:
GiNaC::ex m_expression;
GiNaC::symtab m_exprtable;
try {
m_expression = l_parser( "a*x^3+b*y^4" );
m_exprtable = l_parser.get_syms();
} catch (...) {}
GiNaC::ex l_full;
GiNaC::symtab l_table(m_exprtable);
l_table["formula"] = m_expression;
GiNaC::parser l_parser(l_table);
try {
l_full = l_parser( "0.5*(t - formula)^2" ); // (*)
} catch (...) {}
std::cout << l_full << std::endl;
I using the version 1.5.8 (on 1.5.7 I had got a compiler error).
Is this the correct way for concating two symbolic expression?
Do I have forgot anything?
Thanks
Phil
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