Remove -m64 compiler flag that is no longer necessary

Author: Mark Wieczorek

Makefile

@@ -172,7 +172,7 @@ FLAKE8_FILES = pyshtools examples/python
 # if the short name of the compiler is in $(F95).
 ifeq ($(findstring gfortran,$(F95)),gfortran)
 	# Default gfortran flags
-	F95FLAGS ?= -m64 -fPIC -O3 -std=gnu -ffast-math
+	F95FLAGS ?= -fPIC -O3 -std=gnu -ffast-math
 	# -march=native
 	MODFLAG = -I$(MODPATH)
 	SYSMODFLAG = -I$(SYSMODPATH)
@@ -181,7 +181,7 @@ ifeq ($(findstring gfortran,$(F95)),gfortran)
 	LAPACK ?= -llapack
 else ifeq ($(findstring f95,$(F95)),f95)
 	# Default Absoft f95 flags
-	F95FLAGS ?= -m64 -O3 -YEXT_NAMES=LCS -YEXT_SFX=_ -fpic -speed_math=10
+	F95FLAGS ?= -O3 -YEXT_NAMES=LCS -YEXT_SFX=_ -fpic -speed_math=10
 	#-march=host
 	MODFLAG = -p $(MODPATH)
 	SYSMODFLAG = -p $(SYSMODPATH)
@@ -190,15 +190,15 @@ else ifeq ($(findstring f95,$(F95)),f95)
 	LAPACK ?= -llapack
 else ifeq ($(findstring ifort,$(F95)),ifort)
 	# Default intel fortran flags
-	F95FLAGS ?= -m64 -fpp -free -O3 -Tf
+	F95FLAGS ?= -fpp -free -O3 -Tf
 	MODFLAG = -I$(MODPATH)
 	SYSMODFLAG = -I$(SYSMODPATH)
 	OPENMPFLAGS ?= -qopenmp
 	LAPACK ?= -mkl
 	BLAS ?=
 else ifeq ($(findstring ifx,$(F95)),ifx)
 	# Default intel fortran flags
-	F95FLAGS ?= -m64 -fpp -free -O3 -Tf
+	F95FLAGS ?= -fpp -free -O3 -Tf
 	MODFLAG = -I$(MODPATH)
 	SYSMODFLAG = -I$(SYSMODPATH)
 	OPENMPFLAGS ?= -qopenmp
@@ -221,7 +221,7 @@ else ifeq ($(findstring pgf90,$(F95)),pgf90)
 	BLAS ?= -lblas
 	LAPACK ?= -llapack
 else ifeq ($(origin F95FLAGS), undefined)
-	F95FLAGS = -m64 -O3
+	F95FLAGS = -O3
 	MODFLAG = -I$(MODPATH)
 	SYSMODFLAG = -I$(SYSMODPATH)
 	OPENMPFLAGS ?=

docs/pages/fortran/fortran-95-problems.md

@@ -3,7 +3,7 @@ title: "Fortran 95 problems"
 keywords: spherical harmonics software package, spherical harmonic transform, legendre functions, multitaper spectral analysis, fortran, Python, gravity, magnetic field
 sidebar: fortran_sidebar
 permalink: fortran-95-problems.html
-summary: 
+summary:
 toc: true
 folder: fortran
 ---
@@ -71,7 +71,7 @@ where the find command searches the directory `/usr`. This pathname can then be
 
 For some compilers, the location of the source file following the compiler name is important. When this is the case, if the source file is not in its correct position, you could receive link errors that resemble the following:
 ```
-gfortran -L../lib -lSHTOOLS TimingAccuracy/TimingAccuracyGLQC.f95 -I../modules/ -L../lib -lfftw3 -lm -m64 -O3 -o TimingAccuracy/TimingAccuracyGLQC
+gfortran -L../lib -lSHTOOLS TimingAccuracy/TimingAccuracyGLQC.f95 -I../modules/ -L../lib -lfftw3 -lm -O3 -o TimingAccuracy/TimingAccuracyGLQC
 /tmp/cchgdOpg.o: In function `MAIN__':
 TimingAccuracyGLQC.f95:(.text+0x5b3): undefined reference to `randomgaussian_'
 TimingAccuracyGLQC.f95:(.text+0xb9b): undefined reference to `shglq_'
@@ -81,7 +81,7 @@ collect2: error: ld returned 1 exit status
 ```
 For this example, successful compilation can be achieved by placing the source file before the library calls:
 ```
-gfortran  TimingAccuracy/TimingAccuracyGLQC.f95 -L../lib -lSHTOOLS -I../modules/ -L../lib -lfftw3 -lm -m64 -O3 -o TimingAccuracy/TimingAccuracyGLQC
+gfortran  TimingAccuracy/TimingAccuracyGLQC.f95 -L../lib -lSHTOOLS -I../modules/ -L../lib -lfftw3 -lm -O3 -o TimingAccuracy/TimingAccuracyGLQC
 ```
 
 ## The linker can't seem to find either the LAPACK, BLAS, or FFTW libraries

docs/pages/fortran/fortran-installing.md

@@ -150,7 +150,7 @@ LAPACK_UNDERSCORE=1  # add an extra underscore to the LAPACK routine names
 ```
 For this case, compiler flags should probably be set so that underscores are not appended to routine names. See [Fortran 95 problems](fortran-95-problems.html) for further information.
 
-To generate 64 bit code, use the compiler option
+To generate 64 bit code (which is usually the default), use the compiler option
 ```bash
 -m64
 ```

docs/pages/fortran/using-with-f95.md

@@ -34,22 +34,22 @@ Typical examples of compiling and linking a program `MyProgram.f95` to the neces
 
 ### gfortran
 ```bash
-gfortran MyProgram.f95 -I$SHTOOLSMODPATH -L$SHTOOLSLIBPATH -lSHTOOLS -lfftw3 -lm -llapack -lblas -O3 -m64 -o MyProgram
+gfortran MyProgram.f95 -I$SHTOOLSMODPATH -L$SHTOOLSLIBPATH -lSHTOOLS -lfftw3 -lm -llapack -lblas -O3 -o MyProgram
 ```
 
 ### Absoft Pro Fortran (f95)
 ```bash
-f95 MyProgram.f95 -p $SHTOOLSMODPATH -L$SHTOOLSLIBPATH -YEXT_NAMES=LCS -YEXT_SFX=_ -lSHTOOLS -lfftw3 -lm -llapack -lblas -O3 -m64 -o MyProgram
+f95 MyProgram.f95 -p $SHTOOLSMODPATH -L$SHTOOLSLIBPATH -YEXT_NAMES=LCS -YEXT_SFX=_ -lSHTOOLS -lfftw3 -lm -llapack -lblas -O3 -o MyProgram
 ```
 
 ### g95
 ```bash
-g95 MyProgram.f95 -I$SHTOOLSMODPATH -L$SHTOOLSLIBPATH -fno-second-underscore -lSHTOOLS -lfftw3 -lm -llapack -lblas -O3 -m64 -o MyProgram
+g95 MyProgram.f95 -I$SHTOOLSMODPATH -L$SHTOOLSLIBPATH -fno-second-underscore -lSHTOOLS -lfftw3 -lm -llapack -lblas -O3 -o MyProgram
 ```
 
 ### Intel Fortran (ifort)
 ```bash
-ifort -fpp -free -I$SHTOOLSMODPATH -L$SHTOOLSLIBPATH -lSHTOOLS -lfftw3 -lm -llapack -lblas -O3 -m64 -Tf MyProgram.f95 -o MyProgram
+ifort -fpp -free -I$SHTOOLSMODPATH -L$SHTOOLSLIBPATH -lSHTOOLS -lfftw3 -lm -llapack -lblas -O3 -Tf MyProgram.f95 -o MyProgram
 ```
 Note that the position of the source file in the above examples might be important for some compilers. Note also that on macOS, linking to the preinstalled LAPACK and BLAS libraries can be accomplished using `-framework Accelerate`. (See [installing SHTOOLS](installing-fortran.html) for more details).