Changeset 12922

Timestamp:

09/25/10 10:10:22 (13 years ago)

Author:

ehuelsmann

Message:

Factor out common code and add documentation to indicate
which part of the CLHS it's implementing.

File:

• trunk/abcl/src/org/armedbear/lisp/MathFunctions.java (modified) (8 diffs)

trunk/abcl/src/org/armedbear/lisp/MathFunctions.java

@@ -38 +38 @@
 public final class MathFunctions
 {
+
+    // Implementation of section 12.1.5.3, which says:
+    // "If the result of any computation would be a complex number whose
+    //  real part is of type rational and whose imaginary part is zero,
+    //  the result is converted to the rational which is the real part."
+    private static final LispObject complexToRealFixup(LispObject result,
+                                                       LispObject arg)
+    {
+        if (result instanceof Complex
+            && ! (arg instanceof Complex)) {
+            Complex c = (Complex)result;
+            LispObject im = c.getImaginaryPart();
+            if (im.zerop())
+                return c.getRealPart();
+        }
+        return result;
+    }
+
     // ### sin
     private static final Primitive SIN = new Primitive("sin", "radians")
@@ -136 +154 @@
         result = result.multiplyBy(Complex.getInstance(Fixnum.ZERO,
                                                        Fixnum.MINUS_ONE));
-        if (result instanceof Complex) {
-            if (arg instanceof Complex)
-                return result;
-            LispObject im = ((Complex)result).getImaginaryPart();
-            if (im.zerop())
-                return ((Complex)result).getRealPart();
-        }
-        return result;
+
+        return complexToRealFixup(result, arg);
     }
 
@@ -178 +190 @@
         }
         result = result.subtract(asin(arg));
-        if (result instanceof Complex) {
-            if (arg instanceof Complex)
-                return result;
-            LispObject im = ((Complex)result).getImaginaryPart();
-            if (im.zerop())
-                return ((Complex)result).getRealPart();
-        }
-        return result;
+
+        return complexToRealFixup(result, arg);
     }
 
@@ -278 +284 @@
         result = result.subtract(exp(arg.multiplyBy(Fixnum.MINUS_ONE)));
         result = result.divideBy(Fixnum.TWO);
-        if (result instanceof Complex) {
-            if (arg instanceof Complex)
-                return result;
-            LispObject im = ((Complex)result).getImaginaryPart();
-            if (im.zerop())
-                return ((Complex)result).getRealPart();
-        }
-        return result;
+
+        return complexToRealFixup(result, arg);
     }
 
@@ -316 +316 @@
         result = result.add(exp(arg.multiplyBy(Fixnum.MINUS_ONE)));
         result = result.divideBy(Fixnum.TWO);
-        if (result instanceof Complex) {
-            if (arg instanceof Complex)
-                return result;
-            LispObject im = ((Complex)result).getImaginaryPart();
-            if (im.zerop())
-                return ((Complex)result).getRealPart();
-        }
-        return result;
+
+        return complexToRealFixup(result, arg);
     }
 
@@ -366 +360 @@
         result = result.add(arg);
         result = log(result);
-        if (result instanceof Complex) {
-            if (arg instanceof Complex)
-                return result;
-            LispObject im = ((Complex)result).getImaginaryPart();
-            if (im.zerop())
-                return ((Complex)result).getRealPart();
-        }
-        return result;
+
+        return complexToRealFixup(result, arg);
     }
 
@@ -403 +391 @@
         result = log(result);
         result = result.multiplyBy(Fixnum.TWO);
-        if (result instanceof Complex) {
-            if (arg instanceof Complex)
-                return result;
-            LispObject im = ((Complex)result).getImaginaryPart();
-            if (im.zerop())
-                return ((Complex)result).getRealPart();
-        }
-        return result;
+
+        return complexToRealFixup(result, arg);
     }
 
@@ -435 +417 @@
         LispObject result = n1.subtract(n2);
         result = result.divideBy(Fixnum.TWO);
-        if (result instanceof Complex) {
-            if (arg instanceof Complex)
-                return result;
-            LispObject im = ((Complex)result).getImaginaryPart();
-            if (im.zerop())
-                return ((Complex)result).getRealPart();
-        }
-        return result;
+
+        return complexToRealFixup(result, arg);
     }