Why do I get unexpected errors when using NaN values in INTERP1?

Why do I get unexpected errors when using NaN values in INTERP1?

Using the INTERP1 function of MATLAB 6.1 (R12.1) with NaN values returns an unusual error:

interp1([NaN 1:4],[2:6],3.5)

 ??? Index into matrix is negative or zero.  See release notes on changes to 

 logical indices.

 Error in ==> D:\Applications\MATLAB\toolbox\matlab\polyfun\interp1.m

 On line 157  ==>             s = u - x(k);

This error can be traced to the results of the HISTC function called earlier within INTERP1:

[n,k] = histc(3.5,[NaN 1:4])

 n =

      0     0     0     0     0

 k =

      0

Answer 1

[MathWorks Support Team]

This bug has been fixed for Release 14 (R14). For previous releases, please read below for any possible workarounds:

INTERP1 is not intended to handle NaN's as input, since NaN values cannot be placed in increasing order (a requirement of INTERP1 and of HISTC). As a workaround, use Inf or -Inf to represent a limit.

Our development staff has been notified and is currently looking into addressing this problem in a future release of MATLAB.