??? Undefined function or method 'isnan' for input arguments of type 'struct'.

I have a structure array, 'AMap'. The elements of 'AMap', which are called 'fitresults', are most often structre arrays themselves, but sometimes they are supposed to be equal to NaN, such as can be seen and verified in the command window:

>> AMap(8,1).fitresults

ans =

     NaN

>> isnan(AMap(8,1).fitresults)

ans =

       1

But when I try to use 'isnan' in an if statement in a forloop in a function,

if(isnan(AMap(i,j).fitresults)==0)

I get the error:

 ??? Undefined function or method 'isnan' for input arguments of type 'struct'.

but as you can see 'isnan' must be defined for structs since I can use isnan on a struct in the command window. What gives? How can I get around this?

thanks in advance,

Rory

Answer 1

[Walter Roberson]

You only tested isnan() for the case where AMap(8,1).fitresults is NaN, and did not test it for the case where it is a structure instead.

I suggest that you change your test to

if isstruct(AMap(i,j).fitresults)

[Rory Staunton]

thanks walter, you beat me to it!!

Answer 2

[Rory Staunton]

When the value of AMap(i,j).fitresults is NaN, then isnan works, because fitresults is not a struct.

When the value of AMap(i,j).fitresults is a struct array, then 'isnan' complains, because it is a struct, and 'isnan' can't work on structs.

My solution is to use 'isstruct' instead. It will give 0 when fitresults = NaN, and 1 when it is a struct.

For my purposes this will suffice...