Initial data commit

Task/Test-integerness/Fortran/test-integerness-1.f

@@ -0,0 +1,28 @@
+      MODULE ZERMELO	!Approach the foundations of mathematics.
+       CONTAINS
+        LOGICAL FUNCTION ISINTEGRAL(X)	!A whole number?
+         REAL*8 X	!Alas, this is not really a REAL number.
+         INTEGER*8 N	!Largest available.
+          IF (ISNAN(X)) THEN	!Avoid some sillyness.
+            ISINTEGRAL = .FALSE.	!And possible error messages.
+          ELSE			!But now it is safe to try.
+            N = KIDINT(X)		!This one truncates.
+            ISINTEGRAL = N .EQ. X	!Any difference?
+          END IF		!A floating-point number may overflow an integer.
+        END FUNCTION ISINTEGRAL	!And even if integral, it will not seem so.
+
+        LOGICAL FUNCTION ISINTEGRALZ(Z)	!For complex numbers, two tests.
+         DOUBLE COMPLEX Z	!Still not really REAL, though.
+          ISINTEGRALZ = ISINTEGRAL(DBLE(Z)) .AND. ISINTEGRAL(DIMAG(Z))	!Separate the parts.
+        END FUNCTION ISINTEGRALZ!No INTEGER COMPLEX type is offered.
+      END MODULE ZERMELO	!Much more mathematics lie elsewhere.
+
+      PROGRAM TEST
+      USE ZERMELO
+      DOUBLE COMPLEX Z
+
+      WRITE (6,*) "See if some numbers are integral..."
+      WRITE (6,*) ISINTEGRAL(666D0),666D0
+      Z = DCMPLX(-3D0,4*ATAN(1D0))
+      WRITE (6,*) ISINTEGRALZ(Z),Z
+      END