Sketch out Spectrum API

4 files changed, 260 insertions, 0 deletions

diff --git a/libcrystfel/CMakeLists.txt b/libcrystfel/CMakeLists.txt
index 97ab8de3..67a20ee5 100644
--- a/libcrystfel/CMakeLists.txt
+++ b/libcrystfel/CMakeLists.txt
@@ -68,6 +68,7 @@ set(LIBCRYSTFEL_SOURCES
     src/taketwo.c
     src/xgandalf.c
     src/rational.c
+    src/spectrum.c
     ${BISON_symopp_OUTPUTS}
     ${FLEX_symopl_OUTPUTS}
 )
@@ -108,6 +109,7 @@ set(LIBCRYSTFEL_HEADERS
     src/taketwo.h
     src/xgandalf.h
     src/rational.h
+    src/spectrum.h
 )
 
 if (DOXYGEN_FOUND)
diff --git a/libcrystfel/doc/index.md b/libcrystfel/doc/index.md
index 3ffb3dc1..a14e62db 100644
--- a/libcrystfel/doc/index.md
+++ b/libcrystfel/doc/index.md
@@ -50,6 +50,7 @@ API documentation
 * \ref predict-refine.h "Prediction refinement"
 * \ref integration.h "Integration of reflections"
 * \ref detector.h "Detector geometry descriptions"
+* \ref spectrum.h "Radiation spectrum object"
 * \ref hdf5-file.h "HDF5 file interface"
 * \ref stream.h "Stream format for indexing/integration results"
 * \ref render.h "Miscellaneous rendering functions (colour scale)"
diff --git a/libcrystfel/src/spectrum.c b/libcrystfel/src/spectrum.c
new file mode 100644
index 00000000..d36ba99d
--- /dev/null
+++ b/libcrystfel/src/spectrum.c
@@ -0,0 +1,170 @@
+/*
+ * spectrum.c
+ *
+ * A class representing a radiation spectrum
+ *
+ * Copyright © 2019 Deutsches Elektronen-Synchrotron DESY,
+ *                  a research centre of the Helmholtz Association.
+ *
+ * Authors:
+ *   2019 Thomas White <taw@physics.org>
+ *
+ * This file is part of CrystFEL.
+ *
+ * CrystFEL is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * CrystFEL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with CrystFEL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "spectrum.h"
+#include "utils.h"
+
+
+/**
+ * \file spectrum.h
+ */
+
+
+enum spectrumrep
+{
+	SPEC_HISTOGRAM,
+	SPEC_GAUSSIANS
+};
+
+struct _spectrum
+{
+	enum spectrumrep rep;
+};
+
+
+/**
+ * Create a new \ref Spectrum.
+ *
+ * \returns The new spectrum, or NULL on failure.
+ *
+ */
+Spectrum *spectrum_new()
+{
+	Spectrum *s;
+
+	s = malloc(sizeof(Spectrum));
+	if ( s == NULL ) return NULL;
+
+	return s;
+}
+
+
+/**
+ * \param s A \ref Spectrum
+ *
+ * Frees a \ref Spectrum.
+ */
+void spectrum_free(Spectrum *s)
+{
+	free(s);
+}
+
+
+/**
+ * \param s A \ref Spectrum
+ * \param tol Fraction of spectrum required
+ *
+ * \returns The number of Gaussians needed to represent at least \p tol
+ * fraction of the total intensity in the spectrum.
+ */
+int spectrum_get_num_gaussians(Spectrum *s, double tol)
+{
+	return 0;
+}
+
+
+/**
+ * \param s A \ref Spectrum
+ * \param n The index number of the required Gaussian
+ *
+ * Returns The \p n-th Gaussian to represent the spectrum.  The Gaussians are
+ * returned in descending order of integrated intensity, indexed from zero.
+ *
+ * If \p n is greater than or equal to the number of Gaussians needed to account
+ * for 100% of the spectrum, the returned Gaussian will have zero height.
+ *
+ * \returns The \p n-th Gaussian.
+ */
+struct gaussian spectrum_get_gaussian(Spectrum *s, int n)
+{
+	struct gaussian g;
+	g.kcen = 0.0;
+	g.sigma = 0.0;
+	g.height = 0.0;
+	return g;
+}
+
+
+/**
+ * \param s A \ref Spectrum
+ * \param k A wavenumber (in 1/metres)
+ *
+ * Returns the spectral density at wavenumber \p k.
+ * To calculate the "amount of intensity" from this, you'll need to multiply
+ * the value by a small width of k.
+ *
+ * \returns The density at \p k.
+ */
+double spectrum_get_density_at_k(Spectrum *s, double k)
+{
+	return 0.0;
+}
+
+
+/**
+ * \param s A \ref Spectrum
+ * \param tol Fraction of spectrum required
+ * \param kmin Location to store minimum k value
+ * \param kmax Location to store maximum k value
+ *
+ * Returns the range of k values needed to capture \p tol of the spectrum.
+ */
+void spectrum_get_range(Spectrum *s, double tol, double *kmin, double *kmax)
+{
+}
+
+
+/**
+ * \param s A \ref Spectrum
+ * \param gs Pointer to array of \ref gaussian structures
+ * \param n_gauss Number of Gaussians in \p gs
+ *
+ * Sets the spectrum in terms of a number of Gaussians.
+ */
+void spectrum_set_gaussians(Spectrum *s, struct gaussian *gs, int n_gauss)
+{
+	/* FIXME: sort them */
+}
+
+
+/**
+ * \param s A \ref Spectrum
+ * \param kcens Pointer to array of k values in the centres of the bins
+ * \param heights Pointer to array of spectral density values
+ * \param nbins Number of bins
+ *
+ * Sets the spectrum in terms of a histogram.
+ */
+void spectrum_set_histogram(Spectrum *s, double *kcens, double *heights,
+                            int nbins)
+{
+}
diff --git a/libcrystfel/src/spectrum.h b/libcrystfel/src/spectrum.h
new file mode 100644
index 00000000..abce55a2
--- /dev/null
+++ b/libcrystfel/src/spectrum.h
@@ -0,0 +1,87 @@
+/*
+ * spectrum.h
+ *
+ * A class representing a radiation spectrum
+ *
+ * Copyright © 2019 Deutsches Elektronen-Synchrotron DESY,
+ *                  a research centre of the Helmholtz Association.
+ *
+ * Authors:
+ *   2019 Thomas White <taw@physics.org>
+ *
+ * This file is part of CrystFEL.
+ *
+ * CrystFEL is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * CrystFEL is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with CrystFEL.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef SPECTRUM_H
+#define SPECTRUM_H
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+
+/**
+ * \file spectrum.h
+ * Data structure representing a radiation spectrum
+ */
+
+/**
+ * This data structure is opaque.  You must use the available accessor functions
+ * to read and write its contents.
+ **/
+typedef struct _spectrum Spectrum;
+
+
+/**
+ * Structure representing a Gaussian distribution of spectral density.
+ */
+struct gaussian
+{
+	double kcen;
+	double sigma;
+	double height;
+};
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern Spectrum *spectrum_new(void);
+
+extern void spectrum_free(Spectrum *s);
+
+extern int spectrum_get_num_gaussians(Spectrum *s, double tol);
+
+extern struct gaussian spectrum_get_gaussian(Spectrum *s, int n);
+
+extern double spectrum_get_density_at_k(Spectrum *s, double k);
+
+extern void spectrum_get_range(Spectrum *s, double tol,
+                               double *kmin, double *kmax);
+
+extern void spectrum_set_gaussians(Spectrum *s, struct gaussian *gs,
+                                   int n_gauss);
+
+extern void spectrum_set_histogram(Spectrum *s, double *kcens, double *heights,
+                                   int nbins);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	/* SPECTRUM_H */