A general function used by HCR_ramp that adjusts the output (e.g., F) by a linear ramp based on
the value of the OCP relative to target and limit values.

`HCRlin(OCP_val, LOCP, TOCP, relF_min = 0, relF_max = 1)`

## Arguments

- OCP_val
The value of the operational control point (OCP).

- LOCP
Numeric, the limit value for the OCP in the HCR.

- TOCP
Numeric, the target value for the OCP in the HCR.

- relF_min
The relative maximum value (e.g. a multiple of FMSY) if `OCP < LOCP`

.

- relF_max
The relative maximum value (e.g. a multiple of FMSY) if `OCP > TOCP`

.

## Value

Numeric adjustment factor.

## Examples

```
#40-10 linear ramp
Brel <- seq(0, 1, length.out = 200)
plot(Brel, HCRlin(Brel, 0.1, 0.4), xlab = "Estimated B/B0", ylab = "Relative change in F",
main = "A 40-10 harvest control rule", type = 'l', col = 'blue')
abline(v = c(0.1,0.4), col = 'red', lty = 2)
```