first Julia set plotted

Fraktalism/.gitignore

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+
+julia
+
+*.pgm

Fraktalism/Makefile

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+
+GFOPT  = -Wall -Wextra -time -g
+
+# ---------------------------------------------
+
+spitpgm.o:	spitpgm.f90 Makefile
+	gfortran $(GFOPT) -c $<
+
+fraktals.o:	fraktals.f90 Makefile
+	gfortran $(GFOPT) -c $<
+
+OBJS = spitpgm.o fraktals.o
+
+# ---------------------------------------------
+
+julia:		julia.f90 Makefile $(OBJS)
+	gfortran $(GFOPT) $<  $(OBJS)    -o $@
+
+# ---------------------------------------------

Fraktalism/fraktals.f90

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+module fraktals
+  implicit none
+  contains
+
+!-----------------------------------------------------
+subroutine simple_julia(pic, cx, cy)
+    implicit none
+    integer, intent(inout), dimension (:,:)  ::  pic
+    real, intent(in)                         ::  cx, cy
+
+    integer      ::  ix, iy, width, height
+    real         ::  fx, fy
+    complex      ::  Z, C
+    integer      ::  iter, maxiter
+
+    width  = ubound(pic, 1)
+    height = ubound(pic, 2)
+    print *, "image size : ", width, height
+    ! print *, "constante  : ", cx, cy
+
+    maxiter = 500
+    C = complex(cx, cy)
+    print *, "C = ", C
+
+    do ix = 1, width
+      fx = (float(ix) / (float(width)/4.0) - 2.0)
+      do iy = 1, height
+        fy = (float(iy) / (float(height)/4.0) - 2.0)
+
+          ! ------ traitement du pixel
+          iter = 0
+          Z = complex(fx, fy)
+          do while ( (modulus2(Z) .LT. 4.0) .AND.     &
+                     (iter < maxiter) )
+            Z = (Z * Z) + C
+            iter = iter + 1
+
+          end do
+
+          pic(ix, iy) = iter
+
+          ! print *, ix, iy, "    ", fx, fy, "    ", iter
+
+      enddo
+    enddo 
+
+end subroutine
+!-----------------------------------------------------
+function dist0 (x, y)
+  implicit none
+  real, intent(in)    :: x, y
+  real                :: dist0
+  dist0 = ( x*x + y*y )
+end function
+
+!-----------------------------------------------------
+function modulus2(pt)
+  implicit none
+  complex, intent(in)    ::   pt
+  real                   ::   modulus2
+  modulus2 = real(pt)*real(pt) + imag(pt)*imag(pt)
+end
+!-----------------------------------------------------
+
+end module fraktals

Fraktalism/julia.f90

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+! 
+!    this is the main programm
+! 
+!-----------------------------------------------------
+
+program julia
+
+    use spitpgm
+    use fraktals
+
+    implicit none
+
+    integer, dimension(640, 480)    ::    picz
+    integer                         ::    argc
+    character(200)                  ::    filename
+
+    argc = IARGC()
+
+    if (1 .NE. argc) then
+      STOP ": JULIA PROGGY NEED A FILENAME"
+    endif
+
+    call getarg(1, filename)
+
+    call simple_julia(picz, 0.3, 0.6)
+    call spit_as_pgm(picz, trim(filename))
+
+end program
+
+!-----------------------------------------------------

Fraktalism/spitpgm.f90

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+module spitpgm
+
+    implicit none
+
+    contains
+
+!-----------------------------------------------------
+
+subroutine spit_as_pgm(pic, fname)
+
+    ! implicit none
+
+    integer, intent(in), dimension (:,:)  ::  pic
+    character (len=*), intent(in)         ::  fname
+
+    integer   :: io, foo
+    integer   :: ix, iy
+    real      :: fk, fpix
+
+    print *, "> spit_as_pgm to ", fname
+
+    open(newunit=io, file=fname)
+    write (io, '(a2)') "P2"
+    write (io, '(i0," ",i0)')  size(pic, 1), size(pic, 2)
+    write (io, '(i0)') 65535
+
+    foo = MAXVAL(pic)
+
+    if (foo .EQ. 0) then
+        print *, " IS SOMETHING WRONG GOING TO HAPPEN ?"
+        do ix = 1, size(pic)
+            write (io, "(i0)") 0
+        enddo
+    else
+        fk = float(foo)  / 65535.0
+        print *, "  max pix value", foo, "  fk =  ", fk
+        do iy = 1, ubound(pic, 2)
+            do ix = 1, ubound(pic, 1)
+                 fpix = float(pic(ix, iy)) / fk
+                 write (io, "(i0)") int(fpix)
+            end do
+        end do
+    endif
+
+    close(io)
+
+end subroutine
+!-----------------------------------------------------
+
+end module spitpgm