Really fixed the atan2(-Pi, 0) bug.

[ginac.git] / ginac / inifcns_trans.cpp

diff --git a/ginac/inifcns_trans.cpp b/ginac/inifcns_trans.cpp
index 3f161d218c068e2a4d016fce5d5cfcb2d32f789e..c8a0a8214ca7f276da625096c36899cdd1be9d78 100644 (file)
--- a/ginac/inifcns_trans.cpp
+++ b/ginac/inifcns_trans.cpp
@@ -822,65 +822,68 @@ static ex atan2_eval(const ex & y, const ex & x)
 {
        if (y.is_zero()) {
 
-               // atan(0, 0) -> 0
+               // atan2(0, 0) -> 0
                if (x.is_zero())
                        return _ex0;
 
-               // atan(0, x), x real and positive -> 0
+               // atan2(0, x), x real and positive -> 0
                if (x.info(info_flags::positive))
                        return _ex0;
 
-               // atan(0, x), x real and negative -> Pi
+               // atan2(0, x), x real and negative -> Pi
                if (x.info(info_flags::negative))
                        return Pi;
        }
 
        if (x.is_zero()) {
 
-               // atan(y, 0), y real and positive -> Pi/2
+               // atan2(y, 0), y real and positive -> Pi/2
                if (y.info(info_flags::positive))
                        return _ex1_2*Pi;
 
-               // atan(y, 0), y real and negative -> -Pi/2
-               if (y.info(info_flags::real) && !y.is_zero())
+               // atan2(y, 0), y real and negative -> -Pi/2
+               if (y.info(info_flags::negative))
                        return _ex_1_2*Pi;
        }
 
        if (y.is_equal(x)) {
 
-               // atan(y, y), y real and positive -> Pi/4
+               // atan2(y, y), y real and positive -> Pi/4
                if (y.info(info_flags::positive))
                        return _ex1_4*Pi;
 
-               // atan(y, y), y real and negative -> -3/4*Pi
+               // atan2(y, y), y real and negative -> -3/4*Pi
                if (y.info(info_flags::negative))
                        return numeric(-3, 4)*Pi;
        }
 
        if (y.is_equal(-x)) {
 
-               // atan(y, -y), y real and positive -> 3*Pi/4
+               // atan2(y, -y), y real and positive -> 3*Pi/4
                if (y.info(info_flags::positive))
                        return numeric(3, 4)*Pi;
 
-               // atan(y, -y), y real and negative -> -Pi/4
+               // atan2(y, -y), y real and negative -> -Pi/4
                if (y.info(info_flags::negative))
                        return _ex_1_4*Pi;
        }
 
-       // atan(float, float) -> float
+       // atan2(float, float) -> float
        if (is_a<numeric>(y) && !y.info(info_flags::crational) &&
            is_a<numeric>(x) && !x.info(info_flags::crational))
                return atan(ex_to<numeric>(y), ex_to<numeric>(x));
 
-       // atan(real, real) -> atan(y/x) +/- Pi
+       // atan2(real, real) -> atan(y/x) +/- Pi
        if (y.info(info_flags::real) && x.info(info_flags::real)) {
                if (x.info(info_flags::positive))
                        return atan(y/x);
-               else if (y.info(info_flags::positive))
-                       return atan(y/x)+Pi;
-               else
-                       return atan(y/x)-Pi;
+
+               if (x.info(info_flags::negative)) {
+                       if (y.info(info_flags::positive))
+                               return atan(y/x)+Pi;
+                       if (y.info(info_flags::negative))
+                               return atan(y/x)-Pi;
+               }
        }
 
        return atan2(y, x).hold();
@@ -891,10 +894,10 @@ static ex atan2_deriv(const ex & y, const ex & x, unsigned deriv_param)
        GINAC_ASSERT(deriv_param<2);
        
        if (deriv_param==0) {
-               // d/dy atan(y,x)
+               // d/dy atan2(y,x)
                return x*power(power(x,_ex2)+power(y,_ex2),_ex_1);
        }
-       // d/dx atan(y,x)
+       // d/dx atan2(y,x)
        return -y*power(power(x,_ex2)+power(y,_ex2),_ex_1);
 }