Matlab的判别和转换函数

Matlab的判别和转换函数ISCHAR True for character array (string).ISCHAR(S) returns 1 if S is a character array and 0 otherwise.ISNUMERIC True for numeric arrays.ISNUMERIC(A) returns 1 if A is a numeric array and 0 otherwise.For example, sparse arrays, and double precision arrays arenumeric while strings, cell arrays, and structure arrays are not.ISLOGICAL True for logical array.ISLOGICAL(X) returns 1 if X is a logical array and 0 otherwise.Logical arrays must be used to perform logical 0-1 indexing.ISNAN True for Not-a-Number.ISNAN(X) returns an array that contains 1's wherethe elements of X are NaN's and 0's where they are not.For example, ISNAN([pi NaN Inf -Inf]) is [0 1 0 0].ISEMPTY True for empty matrix.ISEMPTY(X) returns 1 if X is an empty array and 0 otherwise. An empty array has no elements, that is prod(size(X))==0.ISINF True for infinite elements.ISINF(X) returns an array that contains 1's where theelements of X are +Inf or -Inf and 0's where they are not.For example, ISINF([pi NaN Inf -Inf]) is [0 0 1 1].ISFINITE True for finite elements.ISFINITE(X) returns an array that contains 1's wherethe elements of X are finite and 0's where they are not.For example, ISFINITE([pi NaN Inf -Inf]) is [1 0 0 0].For any X, exactly one of ISFINITE(X), ISINF(X), or ISNAN(X) is 1 for each element.ISOBJECT True for MATLAB objects.ISOBJECT(A) returns 1 if A is a MATLAB object and 0 otherwise.ISSTRUCT True for structures.ISSTRUCT(S) returns 1 if S is a structure and 0 otherwise.ISCELL True for cell array.ISCELL(C) returns 1 if C is a cell array and 0 otherwise.ISJA V A True for Java object arraysISJA V A(J) returns 1 if J is a Java object array, and 0 otherwise.ISFIELD True if field is in structure array.F = ISFIELD(S,'field') returns true if 'field' is the name of a fieldin the structure array S.ISSPARSE True for sparse matrix.ISSPARSE(S) is 1 if the storage class of S is sparseand 0 otherwise.DOUBLE Convert to double precision.DOUBLE(X) returns the double precision value for X.If X is already a double precision array, DOUBLE hasno effect.DOUBLE is called for the expressions in FOR, IF, and WHILE loopsif the expression isn't already double precision. DOUBLE shouldbe overloaded for all objects where it makes sense to convert itinto a double precision value.INT2STR Convert integer to string.S = INT2STR(X) rounds the elements of the matrix X tointegers and converts the result into a string matrix.NUM2STR Convert number to string.T = NUM2STR(X) converts the matrix X into a string representation T with about 4 digits and an exponent if required. This is useful for labeling plots with the TITLE, XLABEL, YLABEL, and TEXT commands.T = NUM2STR(X,N) converts the matrix X into a string representation with a maximum N digits of precision. The default number of digits is based on themagnitude of the elements of X.T = NUM2STR(X,FORMAT) uses the format string FORMAT (see SPRINTF for details).Example:num2str(randn(2,2),3) produces the string matrix'-0.433 0.125'' -1.67 0.288'SPRINTF Write formatted data to string.[S,ERRMSG] = SPRINTF(FORMAT,A,...) formats the data in the real part of matrix A (and in any additional matrix arguments), under control of the specified FORMAT string, and returns it in the MATLAB string variable S. ERRMSG is an optional output argument that returns an error message string if an error occurred or an empty matrix if an error did not occur. SPRINTF is the same as FPRINTF except that it returns the data in a MATLAB string variable rather than writing it to a file.FORMAT is a string containing C language conversion specifications. Conversion specifications involve the character %, optional flags, optional width and precision fields, optional subtype specifier, and conversion characters d, i, o, u, x, X, f, e, E, g, G, c, and s.See the Language Reference Guide or a C manual for complete details.The special formats \n,\r,\t,\b,\f can be used to produce linefeed, carriage return, tab, backspace, and formfeed characters respectively.Use \\ to produce a backslash character and %% to produce the percentcharacter.SPRINTF behaves like ANSI C with certain exceptions and extensions.These include:1. ANSI C requires an integer cast of a double argument to correctly use an integer conversion specifier like d. A similiar conversion is required when using such a specifier with non-integral MATLAB values. Use FIX, FLOOR, CEIL or ROUND on a double argument to explicitly convert non-integral MATLAB values to integral values if you plan to use an integer conversion specifier like d. Otherwise, any non-integral MATLAB values will be outputted using the format where the integer conversion specifier letter has been replaced by e.2. The following non-standard subtype specifiers are supported for conversion characters o, u, x, and X.t - The underlying C datatype is a float rather than an unsigned integer.b - The underlying C datatype is a double rather than an unsigned integer. For example, to print out in hex a double value use a format like '%bx'.3. SPRINTF is "vectorized" for the case when A is nonscalar. The format string is recycled through the elements of A (columnwise) until all the elements are used up. It is then recycled in a similar manner through any additional matrix arguments.See the reference page in the online help for other exceptions, extensions, or platform-specific behavior.Examplessprintf('%0.5g',(1+sqrt(5))/2) 1.618sprintf('%0.5g',1/eps) 4.5036e+15sprintf('%15.5f',1/eps) 4503599627370496.00000sprintf('%d',round(pi)) 3sprintf('%s','hello') hellosprintf('The array is %dx%d.',2,3) The array is 2x3.sprintf('\n') is the line termination character on all platforms.FPRINTF Write formatted data to file.COUNT = FPRINTF(FID,FORMAT,A,...) formats the data in the realpart of matrix A (and in any additional matrix arguments), undercontrol of the specified FORMAT string, and writes it to the fileassociated with file identifier FID. COUNT is the number of bytessuccessfully written. FID is an integer file identifier obtainedfrom FOPEN. It can also be 1 for standard output (the screen) or 2for standard error. If FID is omitted, output goes to the screen.FORMAT is a string containing C language conversion specifications.Conversion specifications involve the character %, optional flags,optional width and precision fields, optional subtype specifier, andconversion characters d, i, o, u, x, X, f, e, E, g, G, c, and s.For more details, see the FPRINTF function description in online help(search by Function Name for FPRINTF), or look up FPRINTF in a Clanguage manual.The special formats \n,\r,\t,\b,\f can be used to produce linefeed,carriage return, tab, backspace, and formfeed characters respectively.Use \\ to produce a backslash character and %% to produce the percentcharacter.FPRINTF behaves like ANSI C with certain exceptions and extensions. These include:1. Only the real part of each parameter is processed.2. ANSI C requires an integer cast of a double argument to correctlyuse an integer conversion specifier like d. A similiar conversionis required when using such a specifier with non-integral MATLAB values. Use FIX, FLOOR, CEIL or ROUND on a double argument to explicitly convert non-integral MATLAB values to integral values if you plan to use an integer conversion specifier like d.Otherwise, any non-integral MATLAB values will be outputted using the format where the integer conversion specifier letter has beenreplaced by e.3. The following non-standard subtype specifiers are supported forconversion characters o, u, x, and X.t - The underlying C datatype is a float rather than anunsigned integer.b - The underlying C datatype is a double rather than anunsigned integer.For example, to print out in hex a double value use a format like'%bx'.4. FPRINTF is "vectorized" for the case when A is nonscalar. Theformat string is recycled through the elements of A (columnwise)until all the elements are used up. It is then recycled in a similarmanner through any additional matrix arguments.For example, the statementsx = 0:.1:1; y = [x; exp(x)];fid = fopen('exp.txt','w');fprintf(fid,'%6.2f %12.8f\n',y);fclose(fid);create a text file containing a short table of the exponential function:0.00 1.000000000.10 1.10517092...1.002.71828183See the reference page in the online help for other exceptions,extensions, or platform-specific behavior.See also FSCANF, SPRINTF, FWRITE, DISP, DIARY, SA VE, INPUT. for i=1:10s1=int2str(i);x(i)=input(['please input x(' s1 ')'])end。