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% result = RDDA( file, dim, irec [options] ) |
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% |
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% This routine reads the irec'th record of shape 'dim' from the |
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% direct-access binary file (float or double precision) 'file'. |
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% |
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% Required arguments: |
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% |
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% file - string - name of file to read from |
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% dim - vector - dimensions of the file records and the resulting array |
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% irec - integer - record number in file in which to write data |
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% |
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% Optional arguments (must appear after the required arguments): |
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% prec - string - precision of storage in file. Default = 'real*8'. |
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% ieee - string - IEEE bit-wise representation in file. Default = 'b'. |
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% |
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% 'prec' may take the values: |
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% 'real*4' - floating point, 32 bits. |
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% 'real*8' - floating point, 64 bits - the efault. |
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% |
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% 'ieee' may take values: |
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% 'ieee-be' or 'b' - IEEE floating point with big-endian |
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% byte ordering - the default |
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% 'ieee-le' or 'l' - IEEE floating point with little-endian |
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% byte ordering |
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% 'native' or 'n' - local machine format |
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% 'cray' or 'c' - Cray floating point with big-endian |
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% byte ordering |
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% 'ieee-le.l64' or 'a' - IEEE floating point with little-endian |
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% byte ordering and 64 bit long data type |
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% 'ieee-be.l64' or 's' - IEEE floating point with big-endian byte |
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% ordering and 64 bit long data type. |
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% |
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% eg. T=rdda('t.data',[64 64 32],1); |
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% T=rdda('t.data',[256],4,'real*4'); |
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% T=rdda('t.data',[128 64],2,'real*4','b'); |
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function [arr] = rdda(file,N,k,varargin) |
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|
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% Defaults |
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WORDLENGTH=8; |
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rtype='real*8'; |
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ieee='b'; |
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|
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% Check optional arguments |
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args=char(varargin); |
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while (size(args,1) > 0) |
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if deblank(args(1,:)) == 'real*4' |
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WORDLENGTH=4; |
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rtype='real*4'; |
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elseif deblank(args(1,:)) == 'real*8' |
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WORDLENGTH=8; |
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rtype='real*8'; |
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elseif deblank(args(1,:)) == 'n' | deblank(args(1,:)) == 'native' |
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ieee='n'; |
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elseif deblank(args(1,:)) == 'l' | deblank(args(1,:)) == 'ieee-le' |
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ieee='l'; |
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elseif deblank(args(1,:)) == 'b' | deblank(args(1,:)) == 'ieee-be' |
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ieee='b'; |
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elseif deblank(args(1,:)) == 'c' | deblank(args(1,:)) == 'cray' |
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ieee='c'; |
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elseif deblank(args(1,:)) == 'a' | deblank(args(1,:)) == 'ieee-le.l64' |
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ieee='a'; |
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elseif deblank(args(1,:)) == 's' | deblank(args(1,:)) == 'ieee-be.l64' |
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ieee='s'; |
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else |
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sprintf(['Optional argument ' args(1,:) ' is unknown']) |
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return |
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end |
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args=args(2:end,:); |
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end |
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|
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nnn=prod(N); |
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|
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[fid mess]=fopen(file,'r',ieee); |
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if fid == -1 |
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sprintf('Error while opening file:\n%s',mess) |
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arr=0; |
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return |
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end |
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st=fseek(fid,nnn*(k-1)*WORDLENGTH,'bof'); |
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if st ~= 0 |
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mess=ferror(fid); |
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sprintf('There was an error while positioning the file pointer:\n%s',mess) |
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arr=0; |
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return |
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end |
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[arr count]=fread(fid,nnn,rtype); |
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if count ~= nnn |
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sprintf('Not enough data was available to be read: off EOF?') |
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arr=0; |
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return |
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end |
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st=fclose(fid); |
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arr=reshape(arr,N); |