What are possible issues if MATLAB doesn't recognise a variable?

if strcmp(str(1:3), 'Min') == 1
    VZ = 1;    
end
if strcmp(str(1:3), 'Max') == 1
    VZ = -1;
end
VZ
[k l s] = evIII_weibull('param', mevI, sevI, x0, VZ);
VZ

Good afternoon,

the first time I call "VZ" MATLAB gives me the correct value, but after giving it as input for another function MATLAB doens't know the value anymore. Does anyone know how this is possible? Furthermore the function "evIII_weibull" doesn't accept VZ as input (eventhough I have declared it as input in evIII_weibull.m

This is the error message I get:

??? Input argument "VZ" is undefined.

Please help

[madhan ravi]

The possible reason is that if it doesn't satisfy the if conditions, we may need to see what str contains to narrow it down.

if strcmp(str(1:3), 'Min') == 1
    VZ = 1;    
elseif strcmp(str(1:3), 'Max') == 1
%^^^^------ should be inside the if statement
    VZ = -1;
end

[beginner94]

The str is "Max_deltaTMy_3T" and immediately after the condition VZ is still recognised. It is only after giving it to evIII_weibull as input that MATLAB isn't able anymore to give back the value

[madhan ravi]

Change " " to single quotes ' ' and try again.

[beginner94]

I found the issue, it was a missing input in the evIII_weibull!

Thank you for your help @madhan ravi!

[madhan ravi]

Which was missing ?

[k l s] = evIII_weibull('param', mevI, sevI, x0, VZ);
                                            %    ^^^---- was there already

[Stephen23]

Possibly the problem was that neither of those strcmp conditions was fulfilled, and thus VZ simply remained undefined. In any case, simpler code for those conditions:

if strncmpi(str,'min',3)
    VZ = +1;    
elseif strncmpi(str,'max',3)
    VZ = -1;
end

OR using switch:

switch lower(str(1:3))
    case 'min'
        VZ = +1;
    case 'max'
        VZ = -1;
end
end

[beginner94]

@madhan ravi

Before VZ was missing an input (required, the function is not varargin)

@Stephen Cobeldick

The if condition is working fine, thank you nevertheless!

[beginner94]

@Stephen Cobeldick

If I had been aware that the problem was in evIII_weibull I would of course have provided it. Mercy on beginners :)