GenericMappingTools · seisman · Aug 6, 2020 · Aug 6, 2020 · Aug 6, 2020
diff --git a/doc/rst/source/api.rst b/doc/rst/source/api.rst
@@ -1553,7 +1553,9 @@ in three different situations:
 
 Space will be allocated to hold the results, as needed, and a pointer to
 the object is returned. If there are errors we simply return NULL and
-report the error. The ``mode`` parameter has different meanings for
+report the error. Note that you can read in a GMT_IS_MATRIX either from a text
+table (passing ``geometry`` as GMT_IS_POINT) or from a grid (passing ``geometry``
+as GMT_IS_SURFACE).  The ``mode`` parameter has different meanings for
 different data types.
 
 **Color palette table**.

diff --git a/src/gmt_api.c b/src/gmt_api.c
diff --git a/src/gmt_nc.c b/src/gmt_nc.c
@@ -1685,6 +1685,7 @@ int gmt_nc_write_grd (struct GMT_CTRL *GMT, struct GMT_GRID_HEADER *header, gmt_
 	uint64_t imag_offset;
 	size_t n, nm;
 	size_t width_t, height_t;
+	size_t was_chunk_setting = GMT->current.setting.io_nc4_chunksize[0];	/* Remember current setting */
 	double limit[2];      /* minmax of z variable */
 	gmt_grdfloat *pgrid = NULL;
 	struct GMT_GRID_HEADER_HIDDEN *HH = gmt_get_H_hidden (header);
@@ -1805,6 +1806,8 @@ int gmt_nc_write_grd (struct GMT_CTRL *GMT, struct GMT_GRID_HEADER *header, gmt_
 	if (status != NC_NOERR)
 		goto nc_err;
 
+	GMT->current.setting.io_nc4_chunksize[0] = was_chunk_setting;	/* Restore to previous status */
+
 	return GMT_NOERROR;
 
 nc_err:

diff --git a/src/testapi_grid2matrix.c b/src/testapi_grid2matrix.c
@@ -0,0 +1,26 @@
+#include "gmt_dev.h"
+
+/* Testing reading a grid into a matrix, then writing the matrix to a grid file.
+ * The test script apigrd2mat,sh will compare the two.
+ */
+
+int main () {
+	unsigned int mode = GMT_SESSION_EXTERNAL;
+	double wesn[4] = {-90.0, 120.0, -45.0, 50.0};
+	struct GMT_MATRIX *M1 = NULL, *M2 = NULL;
+	struct GMTAPI_CTRL *API = NULL;
+
+	API = GMT_Create_Session ("test", 2U, mode, NULL);
+
+	/* Read in earth_relief_01d as a matrix from the remote grid */
+	M1 = GMT_Read_Data (API, GMT_IS_MATRIX, GMT_IS_FILE, GMT_IS_SURFACE, GMT_READ_NORMAL, NULL, "@earth_relief_01d_g", NULL);
+	/* Write out the matrix to another grid file */
+	GMT_Write_Data (API, GMT_IS_MATRIX, GMT_IS_FILE, GMT_IS_SURFACE, GMT_WRITE_NORMAL, NULL, "dump_01d.grd", M1);
+	/* Read in earth_relief_01d as a matrix from the remote grid */
+	M2 = GMT_Read_Data (API, GMT_IS_MATRIX, GMT_IS_FILE, GMT_IS_SURFACE, GMT_READ_NORMAL, wesn, "@earth_relief_01d_g", NULL);
+	/* Write out the matrix to another grid file */
+	GMT_Write_Data (API, GMT_IS_MATRIX, GMT_IS_FILE, GMT_IS_SURFACE, GMT_WRITE_NORMAL, NULL, "cut_01d.grd", M2);
+
+	if (GMT_Destroy_Session (API)) return EXIT_FAILURE;
+	exit (0);
+}
diff --git a/src/testapi_imageshading.c b/src/testapi_imageshading.c
@@ -8,7 +8,7 @@ int main (int argc, char **argv) {
 	char args[128] = {""};         	/* String to hold module command arguments */
 	/* Initialize the GMT session */
 	API = GMT_Create_Session ("test", 2U, GMT_SESSION_EXTERNAL, NULL);
-	M = GMT_Read_Data (API, GMT_IS_MATRIX, GMT_IS_FILE, GMT_IS_SURFACE, GMT_READ_NORMAL, NULL, "2d-matrix.txt", NULL);
+	M = GMT_Read_Data (API, GMT_IS_MATRIX, GMT_IS_FILE, GMT_IS_POINT, GMT_READ_NORMAL, NULL, "2d-matrix.txt", NULL);
 	/* Associate our matrix with a virtual file */
 	GMT_Open_VirtualFile (API, GMT_IS_GRID|GMT_VIA_MATRIX, GMT_IS_SURFACE, GMT_IN, M, input);
 

diff --git a/src/testapi_matrix_360.c b/src/testapi_matrix_360.c
@@ -14,7 +14,7 @@ int main () {
 	API = GMT_Create_Session ("test", 2U, mode, NULL);
 
 	/* Read in earth_relief_01d as a matrix from text file and set correct region, inc, registration */
-	M = GMT_Read_Data (API, GMT_IS_MATRIX, GMT_IS_FILE, GMT_IS_SURFACE, GMT_READ_NORMAL, NULL, "@earth_relief_01d.txt", NULL);
+	M = GMT_Read_Data (API, GMT_IS_MATRIX, GMT_IS_FILE, GMT_IS_SURFACE, GMT_READ_NORMAL, NULL, "@earth_relief_01d", NULL);
 	M->range[0] = -180;	M->range[1] = 180; M->range[2] = -90;	M->range[3] = 90.0;
 	M->inc[0] = M->inc[1] = 1.0;
 	M->registration = 1;

diff --git a/src/testapi_matrix_plot.c b/src/testapi_matrix_plot.c
@@ -10,7 +10,7 @@ int main () {
 	char args[128] = {""};         	/* String to hold module command arguments */
 	/* Initialize the GMT session */
 	API = GMT_Create_Session ("test", 0U, GMT_SESSION_EXTERNAL, NULL);
-	M = GMT_Read_Data (API, GMT_IS_MATRIX, GMT_IS_FILE, GMT_IS_SURFACE, GMT_READ_NORMAL, NULL, "@matrix_grid.txt", NULL);
+	M = GMT_Read_Data (API, GMT_IS_MATRIX, GMT_IS_FILE, GMT_IS_POINT, GMT_READ_NORMAL, NULL, "@matrix_grid.txt", NULL);
 	/* Associate our matrix with a virtual file */
 	GMT_Open_VirtualFile (API, GMT_IS_GRID|GMT_VIA_MATRIX, GMT_IS_SURFACE, GMT_IN|GMT_IS_REFERENCE, M, input);
 	/* Prepare the module arguments */

diff --git a/test/api/apimat2grd.ps b/test/api/apimat2grd.ps
diff --git a/test/api/apimat2grd.sh b/test/api/apimat2grd.sh
@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+#
+# Test the C API for passing a global grid as a matrix to grdimage
+# and have the central meridian work correctly.
+
+ps=apimat2grd.ps
+testapi_grid2matrix
+gmt grdimage dump_01d.grd -JQ270/6.5i -Baf -P -K -Cgeo > $ps
+gmt grdimage cut_01d.grd -JQ0/6.5i -Baf -O -Y4.25i -Cgeo >> $ps
diff --git a/test/api/apimat_360.ps b/test/api/apimat_360.ps
diff --git a/test/api/apimat_360_ref.ps b/test/api/apimat_360_ref.ps