fwrite (again)

[Sestak, Dr. Michael]

The "options yrev" should not be used.  Even though your original file has x
and y reversed, fwrite writes the data from grads arrays so everything is in
the order grads expects.  I don't think that would give you the results you
report, though.  The grid should just be skewed around since you are reading
rows and columns in the wrong order.  The little endian may be a problem.
If you are writing and reading the files on the same machine, you don't need
to specify the endian type.  Again, fwrite uses the expected format for the
machine you are on.  Since you only have two variables with one time and
level, there isn't much more that could be wrong.

> -----Original Message-----
> From: Mark Sponsler [mailto:msponsler at COMCAST.NET]
> Sent: Monday, October 17, 2005 2:42 PM
> To: GRADSUSR at LIST.CINECA.IT
> Subject: fwrite (again)
>
>
> Sorry to be so bothersome but I have another simple question
> that I could
> not answer after reviewing the documentation.
>
> When using the fwrite defaults, it streams the data to a
> binary file for
> eventualy re-ingestion into GRADS.  Is some level of fortran
> manipulation
> of the fwrite output required before it can be re-read by Grads?
>
> I ask because I was able to manually generate a control file
> and get Grads
> to read the file producing some results, but the data is way off
> (Significant Wave Heights are all too high and and Direction
> is set to 180
> degrees for all grib points).
>
> Here's my modified control file:
>
> dset grads.fwrite
> undef 9.999E+20
> options little_endian
> options yrev
> ydef 157 linear -78.000000 1
> xdef 288 linear 0.000000 1.250000
> tdef 1 linear 18Z12nov2004 03hr
> zdef 1 linear 1 1
> vars 2
> DIRPWsfc  0 107,1,1  ** surface Primary wave direction [deg]
> HTSGWsfc  0 100,1,1  ** surface Sig height of wind waves and swell [m]
> ENDVARS
>
> Here's the control file for original dataset that fwrite used as it's
> source:
>
> dset nww3.all.grb
> index nww3.all.grb.idx
> undef 9.999E+20
> title nww3.all.grb
> *  produced by grib2ctl v0.9.12.5p33e
> dtype grib 233
> options yrev
> ydef 157 linear -78.000000 1
> xdef 288 linear 0.000000 1.250000
> tdef 61 linear 18Z12nov2004 03hr
> zdef 1 linear 1 1
> vars 11
> DIRPWsfc  0 107,1,1  ** surface Primary wave direction [deg]
> DIRSWsfc  0 109,1,1  ** surface Secondary wave direction [deg]
> HTSGWsfc  0 100,1,1  ** surface Sig height of wind waves and swell [m]
> PERPWsfc  0 108,1,1  ** surface Primary wave mean period [s]
> PERSWsfc  0 110,1,1  ** surface Secondary wave mean period [s]
> UGRDsfc  0 33,1,1  ** surface u wind [m/s]
> VGRDsfc  0 34,1,1  ** surface v wind [m/s]
> WDIRsfc  0 31,1,1  ** surface Wind direction [deg]
> WINDsfc  0 32,1,1  ** surface Wind speed [m/s]
> WVDIRsfc  0 101,1,1  ** surface Direction of wind waves [deg]
> WVPERsfc  0 103,1,1  ** surface Mean period of wind waves [s]
> ENDVARS
>