Write a scalar summary.
tf.compat.v2.summary.scalar( name, data, step=None, description=None )
name: A name for this summary. The summary tag used for TensorBoard will be this name prefixed by any active name scopes.
data: A real numeric scalar value, convertible to a
int64-castable monotonic step value for this summary. If omitted, this defaults to
tf.summary.experimental.get_step(), which must not be None.
description: Optional long-form description for this summary, as a constant
str. Markdown is supported. Defaults to empty.
True on success, or false if no summary was written because no default summary writer was available.
ValueError: if a default writer exists, but no step was provided and