code: def ddspmt(t):
      """SPM canonical HRF dispersion derivative, values for time values `t`
  
      This is the canonical HRF dispersion derivative function as used in SPM.
  
      It is the numerical difference between the HRF sampled at time `t`, and
      values at `t` for another HRF shape with a small change in the peak
      dispersion parameter (``peak_disp`` in func:`spm_hrf_compat`).
      """
      return (spmt(t) - _spm_dd_func(t) / _spm_dd_func_int) / 0.01
  
file_path: nipy/nipy/modalities/fmri/hrf.py
imports: from functools import partial
  import numpy
  import scipy.stats
  import sympy
  from sympy.utilities.lambdify import implemented_function
  from .utils import T, lambdify_t
label_desc: Use image node_id 8 for calling a global function with example usage: ddspmt(t) and returns: unknown