jchristopherson · jchristopherson · Aug 19, 2026 · Aug 16, 2026 · Aug 17, 2026 · Aug 17, 2026
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -3,7 +3,7 @@ cmake_minimum_required(VERSION 3.24)
 project(
     fplot 
     LANGUAGES Fortran
-    VERSION 1.8.12
+    VERSION 1.9.0
 )
 
 

diff --git a/README.md b/README.md
@@ -12,22 +12,66 @@ This library is tailored to write script files for GNUPLOT.  As such, GNUPLOT is
 ## Documentation
 Documentation can be found [here](https://jchristopherson.github.io/fplot/)
 
-## Building FPLOT
-[CMake](https://cmake.org/)This library can be built using CMake.  For instructions see [Running CMake](https://cmake.org/runningcmake/).
+## Building
+FPLOT requires a Fortran compiler with Fortran 2003 support and [Gnuplot](http://www.gnuplot.info/) on your `PATH` to render plots. The CMake and FPM builds retrieve the Fortran library dependencies automatically.
+
+### CMake
+Configure and build the library with CMake 3.24 or newer:
+```sh
+cmake -S . -B build -DBUILD_TESTING=ON -DBUILD_FPLOT_EXAMPLES=ON
+cmake --build build --parallel
+ctest --test-dir build --output-on-failure
+```
+
+Install it to a prefix of your choice:
+```sh
+cmake --install build --prefix /path/to/install
+```
+
+To build a shared library, add `-DBUILD_SHARED_LIBS=ON` to the configure command. Set `BUILD_TESTING` or `BUILD_FPLOT_EXAMPLES` to `OFF` when those targets are not needed.
 
-[FPM](https://github.com/fortran-lang/fpm) can also be used to build this library using the provided fpm.toml.
-```txt
+### FPM
+[FPM](https://github.com/fortran-lang/fpm) can build and test the checked-out repository directly:
+```sh
 fpm build
+fpm test
 ```
-The FPLOT library can be used within your FPM project by adding the following to your fpm.toml file.
+
+Add FPLOT to another FPM project with:
 ```toml
 [dependencies]
 fplot = { git = "https://github.com/jchristopherson/fplot" }
 ```
 
+## Getting Started
+Import `fplot_core` for the primary types, styling constants, and helper routines such as `linspace` and `meshgrid`. A basic 2D plot follows four steps: initialize a plot object, configure its appearance, add one or more data series, and draw it.
+
+```fortran
+use, intrinsic :: iso_fortran_env
+use fplot_core
+
+type(plot_2d) :: plt
+real(real64) :: x(100), y(100)
+
+x = linspace(0.0_real64, 10.0_real64, size(x))
+y = sin(x)
+
+call plt%initialize()
+call plt%set_title("Sine wave")
+call plt%set_x_axis_title("x")
+call plt%set_y_axis_title("sin(x)")
+call plt%push(x, y, lw = 2.0, name = "sin(x)")
+call plt%draw()
+```
+
+`plot_2d%push` creates a line data series directly from `x` and `y`. For more control, create a `plot_data_2d` object, call `define_data`, set properties such as its name, line style, markers, or color, and then pass it to `plot_2d%push`.
+
+Use `plot_3d` for 3D curves and scatter data, `surface_plot` for gridded surfaces, and `plot_polar` for polar coordinates. `plot_data_error_bars`, `plot_data_histogram`, `plot_data_bar`, and `vector_field_plot_data` provide specialized series types. Axis and legend objects are available through `get_x_axis`, `get_y_axis`, and `get_legend` for detailed layout control. Invalid input and allocation failures print a diagnostic and terminate with an `fplot_errors` error code.
+
+The [examples](examples) directory contains complete programs for 2D and 3D plots, surfaces, histograms, error bars, vector fields, and output terminals.
+
 ## External Libraries
 The FPLOT library depends upon the following libraries.
-- [FERROR](https://github.com/jchristopherson/ferror)
 - [COLLECTIONS](https://github.com/jchristopherson/collections)
 - [FSTRING](https://github.com/jchristopherson/fstring)
 - [GEOMPACK](https://github.com/jchristopherson/geompack)
@@ -47,54 +91,22 @@ program example
     ! Local Variables
     real(real64), dimension(n) :: x, y1, y2
     type(plot_2d) :: plt
-    type(plot_data_2d) :: d1, d2
-    class(plot_axis), pointer :: xAxis, yAxis
-    type(legend), pointer :: leg
 
     ! Initialize the plot object
     call plt%initialize()
-
-    ! Define titles
+    call plt%show_legend(.true.)
     call plt%set_title("Example Plot")
-    call plt%set_font_size(14)
-
-    xAxis => plt%get_x_axis()
-    call xAxis%set_title("X Axis")
-
-    yAxis => plt%get_y_axis()
-    call yAxis%set_title("Y Axis")
-
-    ! Establish legend properties
-    leg => plt%get_legend()
-    call leg%set_is_visible(.true.)
-    call leg%set_draw_inside_axes(.false.)
-    call leg%set_horizontal_position(LEGEND_CENTER)
-    call leg%set_vertical_position(LEGEND_BOTTOM)
-    call leg%set_draw_border(.false.)
+    call plt%set_x_axis_title("X Axis")
+    call plt%set_y_axis_title("Y Axis")
 
     ! Define the data, and then add it to the plot
     x = linspace(0.0d0, 10.0d0, n)
     y1 = sin(5.0d0 * x)
     y2 = 2.0d0 * cos(2.0d0 * x)
 
-    call d1%define_data(x, y1)
-    call d2%define_data(x, y2)
-
-    ! Define properties for each data set
-    call d1%set_name("Data Set 1")
-    call d1%set_draw_markers(.true.)
-    call d1%set_marker_frequency(10)
-    call d1%set_marker_style(MARKER_EMPTY_CIRCLE)
-    call d1%set_marker_scaling(2.0)
-
-    call d2%set_name("Data Set 2")
-    call d2%set_line_style(LINE_DASHED)
-    call d2%set_line_width(2.0)
-
-    ! Add the data sets to the plot
-    call plt%push(d1)
-    call plt%push(d2)
-
+    call plt%push(x, y1, lw = 2.0, name = "Data Set 1")
+    call plt%push(x, y2, lw = 2.0, ls = LINE_DASHED, name = "Data Set 2")
+
     ! Let GNUPLOT draw the plot
     call plt%draw()
 end program
@@ -103,10 +115,8 @@ This is the plot resulting from the above program.
 ![](images/example_2d_plot_1.png?raw=true)
 
 ## Example 2
-Another example of a similar two-dimensional plot to the plot in example 1 is given below.  This plot shifts the x-axis to the zero point along the y-axis.
+Another example of a similar two-dimensional plot to the plot in example 1 is given below.  This plot shifts the x-axis to the zero point along the y-axis.  Additionally, this example highlights the use of the plot_axis, legend, and plot_data_2d types to gain more control over the plot.
 ```fortran
-! fplot_2d_2.f90
-
 program example
     use, intrinsic :: iso_fortran_env
     use fplot_core
@@ -178,7 +188,7 @@ The following example illustrates how to create a three-dimensional surface plot
 program example
     use fplot_core
     use iso_fortran_env
-    use forcolormap, only : colormaps_list
+    use forcolormap
     implicit none
 
     ! Parameters
@@ -190,8 +200,6 @@ program example
     real(real64), pointer, dimension(:,:) :: x, y
     real(real64), dimension(m, n) :: z
     type(surface_plot) :: plt
-    type(surface_plot_data) :: d1
-    class(plot_axis), pointer :: xAxis, yAxis, zAxis
     type(custom_colormap) :: map
     type(cmap) :: colors
 
@@ -207,30 +215,21 @@ program example
     ! Initialize the plot
     call plt%initialize()
     call plt%set_colormap(map)
+    call plt%set_x_axis_title("X Axis")
+    call plt%set_y_axis_title("Y Axis")
+    call plt%set_z_axis_title("Z Axis")
+    call plt%set_title("Custom Colormap")
 
     ! Establish lighting
     call plt%set_use_lighting(.true.)
 
     ! Set the orientation of the plot
     call plt%set_elevation(20.0d0)
     call plt%set_azimuth(30.0d0)
-
-    ! Define titles
-    call plt%set_title("Example Plot")
-
-    xAxis => plt%get_x_axis()
-    call xAxis%set_title("X Axis")
-
-    yAxis => plt%get_y_axis()
-    call yAxis%set_title("Y Axis")
-
-    zAxis => plt%get_z_axis()
-    call zAxis%set_title("Z Axis")
 
     ! Define the function to plot
     z = sqrt(x**2 + y**2) * sin(x**2 + y**2)
-    call d1%define_data(x, y, z)
-    call plt%push(d1)
+    call plt%push(x, y, z)
 
     ! Draw the plot
     call plt%draw()
@@ -279,7 +278,6 @@ program example
 
     ! Create the plot
     call plt%initialize()
-    call plt%set_font_size(14)
     xAxis => plt%get_x_axis()
     yAxis => plt%get_y_axis()
 
@@ -330,7 +328,6 @@ program example
     real(real64), parameter :: pi = 2.0d0 * acos(0.0d0)
     real(real64) :: t(npts), x(npts)
     type(plot_polar) :: plt
-    type(plot_data_2d) :: pd
 
     ! Create a function to plot
     t = linspace(-2.0d0 * pi, 2.0d0 * pi, npts)
@@ -342,10 +339,7 @@ program example
     call plt%set_title("Polar Plot Example")
     call plt%set_autoscale(.false.)
     call plt%set_radial_limits([0.0d0, 6.0d0])
-
-    call pd%define_data(t, x)
-    call pd%set_line_width(2.0)
-    call plt%push(pd)
+    call plt%push(t, x, lw = 2.0)
     call plt%draw()
 end program
 ```

diff --git a/configure/template.cmake b/configure/template.cmake
@@ -1,7 +1,6 @@
 @PACKAGE_INIT@
 
 include(CMakeFindDependencyMacro)
-find_dependency(ferror QUIET)
 find_dependency(collections QUIET)
 find_dependency(geompack QUIET)
 find_dependency(fstring QUIET)

diff --git a/doc/src/fplot_colormap.f90 b/doc/src/fplot_colormap.f90
@@ -4,7 +4,6 @@ module fplot_colormap
     use iso_fortran_env
     use fplot_plot_object
     use strings
-    use ferror
     use fplot_errors
     use fplot_colors
     use forcolormap, cmap => Colormap ! avoid conflict with the internally defined colormap type

diff --git a/doc/src/fplot_delaunay_tri_surface.f90 b/doc/src/fplot_delaunay_tri_surface.f90
@@ -5,7 +5,6 @@ module fplot_delaunay_tri_surface
     use ieee_arithmetic
     use fplot_triangulations_delaunay_2d
     use fplot_errors
-    use ferror
     implicit none
     private
     public :: delaunay_tri_surface

diff --git a/doc/src/fplot_errors.f90 b/doc/src/fplot_errors.f90
@@ -1,8 +1,12 @@
 module fplot_errors
     use iso_fortran_env
-    use ferror
     implicit none
 
+    type :: errors
+    contains
+        procedure :: report_error
+    end type
+
 ! ******************************************************************************
 ! ERROR CODES
 ! ------------------------------------------------------------------------------
@@ -19,6 +23,17 @@ module fplot_errors
         !! Occurs if there is a GNUPLOT file error.
 
 contains
+! ------------------------------------------------------------------------------
+subroutine report_error(this, fcn, msg, code)
+    class(errors), intent(inout) :: this
+    character(len = *), intent(in) :: fcn
+    character(len = *), intent(in) :: msg
+    integer(int32), intent(in) :: code
+
+    write(error_unit, '(A)') trim(fcn) // ': ' // trim(msg)
+    error stop code
+end subroutine
+
 ! ------------------------------------------------------------------------------
 subroutine report_memory_error(err, fcn, flag)
     !! Reports a memory allocation error.
@@ -33,7 +48,7 @@ subroutine report_memory_error(err, fcn, flag)
     character(len = 256) :: msg
 
     ! Define the error message
-    write(100, msg) "Memory allocation error returning flag ", flag, "."
+    write(msg, 100) "Memory allocation error returning flag ", flag, "."
     call err%report_error(fcn, trim(msg), PLOT_OUT_OF_MEMORY_ERROR)
 
     ! Formatting
@@ -56,7 +71,7 @@ subroutine report_file_create_error(err, fcn, fname, flag)
     character(len = 2048) :: msg
 
     ! Define the error message
-    write(100, msg) "File ", fname, " could not be created.  The error flag ", &
+    write(msg, 100) "File ", fname, " could not be created.  The error flag ", &
         flag, " was returned."
     call err%report_error(fcn, trim(msg), PLOT_GNUPLOT_FILE_ERROR)
 
@@ -82,7 +97,7 @@ subroutine report_array_size_mismatch_error(err, fcn, name, expected, actual)
     character(len = 256) :: msg
 
     ! Define the message
-    write(100, msg) "Array ", name, " was found to be of length ", actual, &
+    write(msg, 100) "Array ", name, " was found to be of length ", actual, &
         ", but was expected to be of length ", expected, "."
     call err%report_error(fcn, trim(msg), PLOT_ARRAY_SIZE_MISMATCH_ERROR)
 
@@ -113,7 +128,7 @@ subroutine report_matrix_size_mismatch_error(err, fcn, name, mexp, nexp, &
     character(len = 256) :: msg
 
     ! Define the error
-    write(100, msg) "Matrix ", name, " was expected to be of size ", mexp, &
+    write(msg, 100) "Matrix ", name, " was expected to be of size ", mexp, &
         "-by-", nexp, ", but was found to be of size ", mact, "-by-", nact, "."
     call err%report_error(fcn, trim(msg), PLOT_ARRAY_SIZE_MISMATCH_ERROR)
 

diff --git a/doc/src/fplot_filled_plot_data.f90 b/doc/src/fplot_filled_plot_data.f90
@@ -5,7 +5,6 @@ module fplot_filled_plot_data
     use fplot_plot_data
     use fplot_errors
     use fplot_colors
-    use ferror
     use strings
     implicit none
     private

diff --git a/doc/src/fplot_multiplot.f90 b/doc/src/fplot_multiplot.f90
@@ -13,7 +13,6 @@ module fplot_multiplot
     use fplot_constants
     use fplot_errors
     use collections
-    use ferror
     use strings
     implicit none
     private

diff --git a/doc/src/fplot_plot.f90 b/doc/src/fplot_plot.f90
@@ -18,7 +18,6 @@ module fplot_plot
     use fplot_label
     use fplot_arrow
     use fplot_plot_data_function
-    use ferror
     use strings
     use collections
     implicit none

diff --git a/doc/src/fplot_plot_2d.f90 b/doc/src/fplot_plot_2d.f90
@@ -6,7 +6,6 @@ module fplot_plot_2d
     use fplot_errors
     use fplot_plot_axis
     use fplot_legend
-    use ferror
     use strings
     implicit none
     private
@@ -110,7 +109,6 @@ subroutine p2d_init(this, term, fname, err)
         ! Initialize the base class
         ! call plt_init(this, term, fname, errmgr)
         call this%plot%initialize(term, fname, errmgr)
-        if (errmgr%has_error_occurred()) return
 
         ! Process
         flag = 0

diff --git a/doc/src/fplot_plot_3d.f90 b/doc/src/fplot_plot_3d.f90
@@ -8,7 +8,6 @@ module fplot_plot_3d
     use fplot_constants
     use fplot_plot_data
     use fplot_legend
-    use ferror
     use strings
     implicit none
     private
@@ -112,7 +111,6 @@ subroutine p3d_init(this, term, fname, err)
         ! Initialize the base class
         ! call plt_init(this, term, fname, errmgr)
         call this%plot%initialize(term, fname, errmgr)
-        if (errmgr%has_error_occurred()) return
 
         ! Process
         flag = 0

diff --git a/doc/src/fplot_plot_data.f90 b/doc/src/fplot_plot_data.f90
@@ -6,7 +6,6 @@ module fplot_plot_data
     use fplot_constants
     use fplot_colors
     use strings
-    use ferror
     use fplot_errors
     implicit none
     private