naginterfaces.library.specfun.opt_​binary_​con_​price

naginterfaces.library.specfun.opt_binary_con_price(calput, x, s, k, t, sigma, r, q)

opt_binary_con_price computes the price of a binary or digital cash-or-nothing option.

For full information please refer to the NAG Library document for s30ca

https://support.nag.com/numeric/nl/nagdoc_30.3/flhtml/s/s30caf.html

Parameters

calputstr, length 1

Determines whether the option is a call or a put.

$calput=\text{‘C'}$

A call; the holder has a right to buy.

$calput=\text{‘P'}$

A put; the holder has a right to sell.

xfloat, array-like, shape $\left(m\right)$

$x[i-1]$ must contain $X_{\text{i}}$, the $\text{i}$th strike price, for $\text{i}=1,2,\dots ,m$.

sfloat

$S$, the price of the underlying asset.

kfloat

The amount, $K$, to be paid at expiration if the option is in-the-money, i.e., if $s>x[\text{i}-1]$ when $calput=\text{‘C'}$, or if $s<x[\text{i}-1]$ when $calput=\text{‘P'}$, for $\text{i}=1,2,\dots ,m$.

tfloat, array-like, shape $\left(n\right)$

$t[i-1]$ must contain $T_{\text{i}}$, the $\text{i}$th time, in years, to expiry, for $\text{i}=1,2,\dots ,n$.

sigmafloat

$\sigma$, the volatility of the underlying asset. Note that a rate of 15% should be entered as $0.15$.

rfloat

$r$, the annual risk-free interest rate, continuously compounded. Note that a rate of 5% should be entered as $0.05$.

qfloat

$q$, the annual continuous yield rate. Note that a rate of 8% should be entered as $0.08$.

Returns

pfloat, ndarray, shape $(m,n)$

$p[i-1,j-1]$ contains $P_{ij}$, the option price evaluated for the strike price $x_i$ at expiry $t_j$ for $i=1,2,\dots ,m$ and $j=1,2,\dots ,n$.

Raises

NagValueError

(errno $1$)

On entry, $calput=⟨value⟩$.

Constraint: $calput=\text{‘C'}\text{or}\text{‘P'}$.

(errno $2$)

On entry, $m=⟨value⟩$.

Constraint: $m\ge 1$.

(errno $3$)

On entry, $n=⟨value⟩$.

Constraint: $n\ge 1$.

(errno $4$)

On entry, $x[⟨value⟩]=⟨value⟩$.

Constraint: $x\left[i\right]\ge ⟨value⟩$ and $x\left[i\right]\le ⟨value⟩$.

(errno $5$)

On entry, $s=⟨value⟩$.

Constraint: $s\ge ⟨value⟩$ and $s\le ⟨value⟩$.

(errno $6$)

On entry, $k=⟨value⟩$.

Constraint: $k\ge 0.0$.

(errno $7$)

On entry, $t[⟨value⟩]=⟨value⟩$.

Constraint: $t\left[i\right]\ge ⟨value⟩$.

(errno $8$)

On entry, $sigma=⟨value⟩$.

Constraint: $sigma>0.0$.

(errno $9$)

On entry, $r=⟨value⟩$.

Constraint: $r\ge 0.0$.

(errno $10$)

On entry, $q=⟨value⟩$.

Constraint: $q\ge 0.0$.

Notes

opt_binary_con_price computes the price of a binary or digital cash-or-nothing option which pays a fixed amount, $K$, at expiration if the option is in-the-money (see the S Introduction). For a strike price, $X$, underlying asset price, $S$, and time to expiry, $T$, the payoff is, therefore, $K$, if $S>X$ for a call or $S<X$ for a put. Nothing is paid out when this condition is not met.

The price of a call with volatility, $\sigma$, risk-free interest rate, $r$, and annualised dividend yield, $q$, is

$$P_{call}=K{e}^{-rT}\Phi \left(d_2\right)$$

and for a put,

$$P_{put}=K{e}^{-rT}\Phi (-d_2)$$

where $\Phi$ is the cumulative Normal distribution function,

$$\Phi \left(x\right)=\frac{1}{\sqrt{2\pi }}{\int }_{-\infty }^x(-y^2/2)dy\text{,}$$

and

$$d_2=\frac{ln\left(S/X\right)+(r-q-{\sigma }^2/2)T}{\sigma \sqrt{T}}\text{.}$$

The option price $P_{ij}=P(X=X_i,T=T_j)$ is computed for each strike price in a set $X_i$, $i=1,2,\dots ,m$, and for each expiry time in a set $T_j$, $j=1,2,\dots ,n$.

References

Reiner, E and Rubinstein, M, 1991, Unscrambling the binary code, Risk (4)