More evaluation rules: abs(x^n) => abs(x)^n (x > 0, n is real).

A simple test is added as well.

Signed-off-by: Vladimir V. Kisil <kisilv@maths.leeds.ac.uk>

diff --git a/check/exam_inifcns.cpp b/check/exam_inifcns.cpp
index ba1ba9a6b26acd22044f0ef4e6a7086ea4c52d39..994aa3444d6cf6e16ed2fd321897a433d3de4f17 100644 (file)
--- a/check/exam_inifcns.cpp
+++ b/check/exam_inifcns.cpp
@@ -219,11 +219,35 @@ static unsigned inifcns_consist_zeta()
        return result;
 }
 
        return result;
 }
 

+static unsigned inifcns_consist_abs()
+{
+       unsigned result = 0;
+       realsymbol a("a"), b("b"), x("x"), y("y");
+       possymbol p("p");
+
+       if (!abs(exp(x+I*y)).eval().is_equal(exp(x)))
+               ++result;
+
+       if (!abs(pow(p,a+I*b)).eval().is_equal(pow(p,a)))
+               ++result;
+
+       // also checks that abs(p)=p
+       if (!abs(pow(p,a+I*b)).eval().is_equal(pow(p,a)))
+               ++result;
+
+       if (!abs(pow(x+I*y,a)).eval().is_equal(pow(abs(x+I*y),a)))
+               ++result;
+
+       // it is not necessary a simplification if the following is really evaluated
+       if (!abs(pow(x+I*y,a+I*b)).eval().is_equal(abs(pow(x+I*y,a+I*b))))
+               ++result;
+
+}
+

 static unsigned inifcns_consist_various()
 {
        unsigned result = 0;
        symbol n;
 static unsigned inifcns_consist_various()
 {
        unsigned result = 0;
        symbol n;

-       ex e;

        
        if ( binomial(n, 0) != 1 ) {
                clog << "ERROR: binomial(n,0) != 1" << endl;            
        
        if ( binomial(n, 0) != 1 ) {
                clog << "ERROR: binomial(n,0) != 1" << endl;            


@@ -243,6 +267,7 @@ unsigned exam_inifcns()
        result += inifcns_consist_gamma();  cout << '.' << flush;
        result += inifcns_consist_psi();  cout << '.' << flush;
        result += inifcns_consist_zeta();  cout << '.' << flush;
        result += inifcns_consist_gamma();  cout << '.' << flush;
        result += inifcns_consist_psi();  cout << '.' << flush;
        result += inifcns_consist_zeta();  cout << '.' << flush;

+       result += inifcns_consist_abs();  cout << '.' << flush;

        result += inifcns_consist_various();  cout << '.' << flush;
        
        return result;
        result += inifcns_consist_various();  cout << '.' << flush;
        
        return result;

diff --git a/ginac/inifcns.cpp b/ginac/inifcns.cpp
index 8103cd86bf3ec12ad02a2ebec48aff1b122b0c49..0cb2abbd744798bdc61b38348ad71e84e836bc8c 100644 (file)
--- a/ginac/inifcns.cpp
+++ b/ginac/inifcns.cpp
@@ -197,6 +197,16 @@ static ex abs_eval(const ex & arg)
        if (is_ex_the_function(arg, abs))
                return arg;
 
        if (is_ex_the_function(arg, abs))
                return arg;
 

+       if (is_ex_the_function(arg, exp))
+               return exp(arg.op(0).real_part());
+
+       if (is_exactly_a<power>(arg)) {
+               const ex& base = arg.op(0);
+               const ex& exponent = arg.op(1);
+               if (base.info(info_flags::positive) || exponent.info(info_flags::real))
+                       return pow(abs(base), exponent.real_part());
+       }
+

        return abs(arg).hold();
 }
 
        return abs(arg).hold();
 }