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High Throughput Exponential (Clock-Driven Logic)

Last Modified: September 10, 2016

Computes the value of e raised to a specified power.

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x

Input to this function. x must be in the range [-1, 1).

This input supports only scalar values of the fixed-point data type.

Computing exp(x) When x is Outside the Valid Range

Complete the following steps to compute exp(x when x is outside the range [-1, 1):

  1. Find an integer q and a real number r, where r is in the range [0, ln(2)), such that x = q * ln(2) + r.
  2. Compute 2q * exp(r), which is equivalent to exp(x). Because r is in the valid range of [-1, 1), you can then use this node to compute exp(r).

Input Coercion

The CORDIC algorithm represents x internally as a fixed-point number with a 1-bit integer word length. The word length of x must be less than or equal to 64 bits, which means the fractional word length must be less than or equal to 63 bits. If you wire a value to x that has a fractional word length greater than 63 bits, this node rounds off the lower bits to achieve a fractional word length of 63 bits. For example, if you wire a fixed-point data type with a configuration of I60<-5, 55> to x, this node coerces the configuration to be I58<-5,53>.

If you wire a fixed-point data type to x with a fractional word length greater than 63 bits and an integer word length less than -62 bits, this node coerces the configuration to be I1<-62, 63> if the data type is signed. If the data type is unsigned, the coerced configuration is U1<-62, 63>.

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input valid

A Boolean that describes whether the next data point has arrived for processing. Wire the output valid output of an upstream node to this input to transfer data from the upstream node to this node.

TRUE The next data point has arrived for processing.
FALSE The next data point has not arrived for processing.
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ready for output

A Boolean that defines whether downstream nodes are ready for this node to return a new value. Use a Feedback Node to wire the ready for input output of a downstream node to this input of the current node.

True Downstream nodes are ready for this node to return a new value.
False Downstream nodes are not ready for this node to return a new value.
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Note  

If this input is False during a given cycle, the output valid output returns False during that cycle.

Default: True

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exp(x)

e raised to the power of x.

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output valid

A Boolean that indicates whether this node has computed a result that downstream nodes can use. Wire this output to the input valid input of a downstream node to transfer data from the node to the downstream node.

True The node has computed a result that downstream nodes can use.
False This node has not computed a result that downstream nodes can use. Any data output returns an undefined value. The undefined value returned by a data output may differ between simulation and hardware.
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ready for input

A Boolean that indicates whether this node is ready to accept new input data. Use a Feedback Node to wire this output to the ready for output input of an upstream node.

True The node is ready to accept new input data.
False The node is not ready to accept new input data.
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Note  

If this output returns False during a given cycle, this node discards any data that other nodes send to this node during the following cycle. This node discards the data even if input valid is True during the following cycle.

Where This Node Can Run:

Desktop OS: none

FPGA: All devices


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