fixes #1006 (#1041)

Author: martin-henz

xml/chapter2/section4/subsection2.xml

@@ -230,7 +230,7 @@ function magnitude_rectangular(z) {
                      square(imag_part_rectangular(z)));
 }
 function angle_rectangular(z) {
-    return math_atan(imag_part_rectangular(z),
+    return math_atan2(imag_part_rectangular(z),
                      real_part_rectangular(z));
 }
 function make_from_real_imag_rectangular(x, y) {
@@ -297,7 +297,7 @@ function angle_polar(z) { return tail(z); }
 function make_from_real_imag_polar(x, y) {
     return attach_tag("polar",
                       pair(math_sqrt(square(x) + square(y)),
-                           math_atan(y, x)));
+                           math_atan2(y, x)));
 }
 <ALLOW_BREAK/>
 function make_from_mag_ang_polar(r, a) {

xml/chapter2/section4/subsection3.xml

@@ -362,7 +362,7 @@ function install_rectangular_package() {
         return math_sqrt(square(real_part(z)) + square(imag_part(z)));
     }
     function angle(z) {
-        return math_atan(imag_part(z), real_part(z));
+        return math_atan2(imag_part(z), real_part(z));
     }
     function make_from_mag_ang(r, a) {
         return pair(r * math_cos(a), r * math_sin(a));
@@ -508,7 +508,7 @@ function install_polar_package() {
     }
     function make_from_real_imag(x, y) {
         return pair(math_sqrt(square(x) + square(y)),
-                    math_atan(y, x));
+                    math_atan2(y, x));
     }
 
     // interface to the rest of the system
@@ -1551,7 +1551,7 @@ function make_from_real_imag(x, y) {
                : op === "magnitude"
                ? math_sqrt(square(x) + square(y))
                : op === "angle"
-               ? math_atan(y, x)
+               ? math_atan2(y, x)
                : error(op, "unknown op -- make_from_real_imag");
     }
     return dispatch;
@@ -1567,7 +1567,7 @@ function make_from_real_imag(x, y) {
                : op === "magnitude"
                ? math_sqrt(square(x) + square(y))
                : op === "angle"
-               ? math_atan(y, x)
+               ? math_atan2(y, x)
                : error(op, "unknown op -- make_from_real_imag");
     }
     return dispatch;
@@ -1696,7 +1696,7 @@ function install_rectangular_package() {
                    square(imag_part(z)));
     }
     function angle(z) {
-        return math_atan(imag_part(z), real_part(z));
+        return math_atan2(imag_part(z), real_part(z));
     }
     function make_from_mag_ang(r, a) {
         return pair(r * math_cos(a), r * math_sin(a));
@@ -1730,7 +1730,7 @@ function install_polar_package() {
     }
     function make_from_real_imag(x, y) {
        return pair(math_sqrt(square(x) + square(y)),
-                   math_atan(y, x));
+                   math_atan2(y, x));
     }
 
     // interface to the rest of the system

xml/chapter2/section5/subsection2.xml

@@ -481,7 +481,7 @@ function install_rectangular_package() {
                    square(imag_part(z)));
     }
     function angle(z) {
-        return math_atan(imag_part(z), real_part(z));
+        return math_atan2(imag_part(z), real_part(z));
     }
     function make_from_mag_ang(r, a) {
         return pair(r * math_cos(a), r * math_sin(a));
@@ -515,7 +515,7 @@ function install_polar_package() {
     }
     function make_from_real_imag(x, y) {
         return pair(math_sqrt(square(x) + square(y)),
-                    math_atan(y, x));
+                    math_atan2(y, x));
     }
 
     // interface to the rest of the system