Previous topic


Next topic




Set the floating-point error callback function or log object.

There are two ways to capture floating-point error messages. The first is to set the error-handler to ‘call’, using seterr. Then, set the function to call using this function.

The second is to set the error-handler to ‘log’, using seterr. Floating-point errors then trigger a call to the ‘write’ method of the provided object.

funccallable f(err, flag) or object with write method

Function to call upon floating-point errors (‘call’-mode) or object whose ‘write’ method is used to log such message (‘log’-mode).

The call function takes two arguments. The first is a string describing the type of error (such as “divide by zero”, “overflow”, “underflow”, or “invalid value”), and the second is the status flag. The flag is a byte, whose four least-significant bits indicate the type of error, one of “divide”, “over”, “under”, “invalid”:

[0 0 0 0 divide over under invalid]

In other words, flags = divide + 2*over + 4*under + 8*invalid.

If an object is provided, its write method should take one argument, a string.

hcallable, log instance or None

The old error handler.

See also

seterr, geterr, geterrcall


Callback upon error:

>>> def err_handler(type, flag):
...     print("Floating point error (%s), with flag %s" % (type, flag))
>>> saved_handler = np.seterrcall(err_handler)
>>> save_err = np.seterr(all='call')
>>> from collections import OrderedDict
>>> np.array([1, 2, 3]) / 0.0
Floating point error (divide by zero), with flag 1
array([inf, inf, inf])
>>> np.seterrcall(saved_handler)
<function err_handler at 0x...>
>>> OrderedDict(sorted(np.seterr(**save_err).items()))
OrderedDict([('divide', 'call'), ('invalid', 'call'), ('over', 'call'), ('under', 'call')])

Log error message:

>>> class Log:
...     def write(self, msg):
...         print("LOG: %s" % msg)
>>> log = Log()
>>> saved_handler = np.seterrcall(log)
>>> save_err = np.seterr(all='log')
>>> np.array([1, 2, 3]) / 0.0
LOG: Warning: divide by zero encountered in true_divide
array([inf, inf, inf])
>>> np.seterrcall(saved_handler)
<numpy.core.numeric.Log object at 0x...>
>>> OrderedDict(sorted(np.seterr(**save_err).items()))
OrderedDict([('divide', 'log'), ('invalid', 'log'), ('over', 'log'), ('under', 'log')])