# Cos

## Description

The Cos block computes the cosine of input signal. The block uses the coordinate rotation digital computer (CORDIC) approximation method. For more information, see CORDIC approximation method in Algorithms. The block has control signals that indicate whether the input and output data are valid. You can also specify the number of iterations of the algorithm and the latency strategy.

To use this block in your Simulink^{®} model, open the `HDLMathLib`

library by entering this command
in the MATLAB^{®} Command
Window:

`open_system('HDLMathLib')`

### Latency Considerations

You can simulate the Cos block with latency. This block is a masked subsystem that
contains a MATLAB Function block,
`LumpLatency`

. The subsystem uses this MATLAB Function block to compute
the latency based on the **Number of iterations**. To view the function
that computes the latency of the block, open the `LumpLatency`

block in the
masked subsystem. To view inside the mask, click the ⇩ icon on the block.

The maximum latency *L _{Max}* of Cos block is given
by this equation:

*L _{Max}* =

*N*+ 1

where *N* is the value of the **Number of iterations**
parameter.

The minimum latency *L _{Min}* of Cos block is

`2`

when **Number of iterations**is less than or equal to

`2`

. For the number of iterations greater than `2`

, the
minimum latency is given by this equation:*L _{Min}* = 2 +

`ceil`

((*N*-1) / 3)

The block supports four latency modes. You can specify a custom latency value by setting
the **Latency Strategy** parameter to `Custom`

.
For more information, see Custom latency.

## Limitations

The block does not support floating-point data types, such as

`half`

,`single`

, and`double`

.

## Ports

### Input

### Output

## Parameters

## Tips

The block supports HDL code generation using HDL Coder™. HDL Coder provides additional configuration options that affect HDL implementation and synthesized logic. For more information, see HDL Block Properties.

## Algorithms

## References

[1] Volder, Jack E., “The CORDIC
Trigonometric Computing Technique.” *IRE Transactions on Electronic
Computers* EC-8 (1959); 330–334.

[2] Andraka, Ray “A Survey of CORDIC Algorithm for FPGA Based Computers.”
*Proceedings of the 1998 ACM/SIGDA Sixth International Symposium on Field
Programmable Gate Arrays*. Feb. 22–24 (1998): 191–200.

[3] Walther, J.S., “A Unified Algorithm for Elementary Functions,” Proceedings of the Spring Joint Computer Conference, May 18-20, 1971: 379–386.

[4] Schelin, Charles W., “Calculator Function Approximation,” *The American
Mathematical Monthly* 90, no. 5 (1983):
317–325.

## Version History

**Introduced in R2020b**