ARGCHK

ARGCHK validates parameters passed to a function.

[ErrorMsg, ErrorNo] = ARGCHK(ParmSpec,FuncName)
returns an error message if any input parameter to the function
FuncName does not meet the specification as set by ParmSpec.

ParmSpec = {x, data type, range, severity, name}

x = parameter to be checked
data type 'real', 'integer', 'scalar', 'string', 'vector', or 'matrix'
range = [a b]; a = lower limit; b = upper limit
severity = 'warning' or 'error'
name = string identifying parameter x e.g. 'X' or 'pCheck'

See ARGCHK help for more details.

Example,

function [a,b] = pol2car(x,y,str)
% This function takes two values x and y and converts them into
% Polar coordinates, a and b if str = 'polar' or into Cartesian
% coordinates if str = 'cartesian'.

error(nargchk(3, 3, nargin)); % check number of input arguments

p(1,:) = {x 'real' [0 1E6] 'warning' 'x'};
p(2,:) = {x 'scalar' [] 'warning' 'x'};
p(3,:) = {y 'real' [0 1E6] 'error' 'y'};
p(4,:) = {y 'scalar' [] 'error' 'y'};
p(5,:) = {str 'string' [{'polar'} {'cartesian'}] 'error' 'str'};

% p is the parameter specification

[ErrorMsg, ErrorNo] = argchk(p,'pol2car');
if isempty(char(ErrorMsg))
switch str
case 'polar'
a = sqrt(x^2 + y^2);
b = angle(x+j*y);
case 'cartesian'
a = x*cos(y);
b = x*sin(y);
end
else
a = [];
b = [];
for i = 1:length(ErrorMsg)
disp([num2str(ErrorNo(i)),' ', char(ErrorMsg(i))]);
end
end

The following errors are returned when the function is incorrectly called with:

>> [u,v] = pol2car(-2,[1:8],'artesian');
1 POL2CAR ERROR: Input parameter x must be between 0 and 1000000.
4 POL2CAR WARNING: Input parameter y must be scalar.
5 POL2CAR ERROR: Input parameter str must be an exact string match.