An approximate approach is to use the Erlang-B formula.

* Numerical analysis is a branch of mathematics, pioneered by celestial mechanicians, for calculating approximate numerical answers ( such as the position of a planet in the sky ) which are too difficult to solve down to a general, exact formula.

A typical pyroxene has mostly silicon in the tetrahedral site and predominately ions with a charge of + 2 in both the X and Y sites, giving the approximate formula XYT < sub > 2 </ sub > O < sub > 6 </ sub >.

When one of the masses is almost negligible compared to the other mass as the case for Earth and Sun, one can approximate the previous formula to get:

Applying the above formula to the 25-meter-diameter antennas often used in radio telescope arrays and satellite ground antennas at a wavelength of 21 cm ( 1. 42 GHz, a common radio astronomy frequency ), yields an approximate maximum gain of 140, 000 times or about 50 dBi ( decibels above the isotropic level ).

Real-time filters can only approximate this ideal, since an ideal sinc filter ( aka rectangular filter ) is non-causal and has an infinite delay, but it is commonly found in conceptual demonstrations or proofs, such as the sampling theorem and the Whittaker – Shannon interpolation formula.

Given the lengths of the sides of any cyclic quadrilateral, Brahmagupta gave an approximate and an exact formula for the figure's area,

where ƒ is a smooth function, you could use the Euler – Maclaurin formula to convert the series into an integral, plus some corrections involving derivatives of S ( x ), then for large values of a you could use " stationary phase " method to calculate the integral and give an approximate evaluation of the sum.

Far away from the aperture, the angle at which the first minimum occurs, measured from the direction of incoming light, is given by the approximate formula:

Dulong suggests the following approximate formula for Q when the oxygen content is less than 10 %:

This approximate formula is for moderate to large sample sizes ; the reference gives the exact formulas for any sample size, and can be applied to heavily autocorrelated time series like Wall Street stock quotes.

If the apparent field of view is known, the actual field of view can be calculated from the following approximate formula:

In nuclear physics, the semi-empirical mass formula ( SEMF ) ( sometimes also called Weizsäcker's formula, or the Bethe-Weizsäcker formula, or the Bethe-Weizsäcker mass formula to distinguish it from the Bethe – Weizsäcker process ) is used to approximate the mass and various other properties of an atomic nucleus.

For example, given a differentiable function with real values, one can approximate for close to by the formula

Virasena gave the approximate formula C = 3d + ( 16d + 16 )/ 113 to relate the circumference of a circle, C, to its diameter, d. For large values of d, this gives the approximation π ≈ 355 / 113 = 3. 14159292 ..., which is more accurate than the approximation π ≈ 3. 1416 given by Aryabhata in the Aryabhatiya.

Expanding in powers of r < sub > s </ sub >/ r, the leading order term in this formula gives the approximate angular deflection δφ for a massless particle coming in from infinity and going back out to infinity:

Although this formula is approximate, it is accurate for most measurements of gravitational lensing, due to the smallness of the ratio r < sub > s </ sub >/ r.

According to Anthony C. Robin, an approximate formula for the capacity of a sealed expanded bag is:

An alternative approach to fuel calculation is to calculate alternate and holding fuel as above, and obtain some estimate of the total trip fuel requirement, either based on previous experience with that route and aircraft type, or by using some approximate formula ; neither method can take much account of weather.

The cement is a mixture of magnesium oxide ( burnt magnesia ) with magnesium chloride with the approximate chemical formula Mg < sub > 4 </ sub > Cl < sub > 2 </ sub >( OH )< sub > 6 </ sub >( H < sub > 2 </ sub > O )< sub > 8 </ sub >, corresponding to a weight ratio of 2. 5 – 3. 5 parts MgO to one part MgCl < sub > 2 </ sub >.

This sequence can be used to approximate the distribution ( i. e., to generate a histogram ), or to compute an integral ( such as an expected value ).

The problem is to compute the approximate probability that in a room of n people, at least two have the same birthday.

The basic problem considered by numerical integration is to compute an approximate solution to a definite integral:

To obtain an approximate expression for the average magnetic field on a railgun armature, we assume that the rail radius is small compared with the rail separation and, by assuming that the railgun rails can be modelled as a pair of semi-infinite conductors, we compute the following integral:

This sequence can be used to approximate the joint distribution ( e. g., to generate a histogram of the distribution ); to approximate the marginal distribution of one of the variables, or some subset of the variables ( for example, the unknown parameters or latent variables ); or to compute an integral ( such as the expected value of one of the variables ).

A quantum computer can simulate a TQFT, and thereby approximate the Jones polynomial, which as far as we know, is hard to compute classically in the worst case scenario.

This category is for fast Fourier transform ( FFT ) algorithms, i. e. algorithms to compute the discrete Fourier transform ( DFT ) in O ( N log N ) time ( or better, for approximate algorithms ), where is the number of discrete points.

Many real situations are very complex and thus modeled approximate on a computer, a model that is computationally feasible to compute is made from the basic laws or from approximate models made from the basic laws.

In this case, the matrix X < sup > T </ sup > X has an inverse, but is ill-conditioned so that a given computer algorithm may or may not be able to compute an approximate inverse, and if it does so the resulting computed inverse may be highly sensitive to slight variations in the data ( due to magnified effects of rounding error ) and so may be very inaccurate.

Those allow to compute the wavelet coefficients, at least some range k = M ,..., J-1, without having to approximate the integrals in the corresponding scalar products.

* STANN: A simple threaded approximate nearest neighbor C ++ library that can compute Euclidean k-nearest neighbor graphs in parallel

If we are given only the SRM value for a beer we can compute the approximate transmission spectrum if the beer has average spectral characteristics simply by taking the antilog of:

It repeatedly replaces two numbers by their arithmetic and geometric mean, in order to approximate their arithmetic-geometric mean.

In the 2002 edition, the glossary says: " An approximate mean value of the nautical mile equal to 6, 080 feet ; the length of a minute of arc along the meridian at latitude 48 °.

By Morpheus's estimation, then, of there being an approximate 200 year difference between the era in the Matrix and the era of the real world, with the knowledge that Neo's time is actually the 6th incarnation of the Matrix ( and an estimated 200 years or so for each incarnation ), that could potentially mean the year in the real world is closer to the year 3399.

The Maryland – Pennsylvania boundary is an east-west line with an approximate mean latitude of 39 ° 43 ′ 20 ″ N ( Datum WGS 84 ).

However, regardless of the culture, all lunar months approximate the mean length of the synodic month, or how long it takes to pass through each phase ( new, half, full moon ) and back again.

It is possible to simplify the computation of the approximate time of syzygy by combining the monthly linear increment to the accumulator for the mean syzygy, with the full moon cycle correction.

If the data are assumed to be normally distributed, quantiles of the normal distribution and the sample mean and standard error can be used to calculate approximate confidence intervals for the mean.

The legal system in England uses the term counsel as an approximate synonym for a barrister-at-law, and may apply it to mean either a single person who pleads a cause, or collectively, the body of barristers engaged in a case.

To obtain a normalized set of weights, required to approximate GPS, a mean packet size must be known.

For example, one common approach, called parametric empirical Bayes point estimation, is to approximate the marginal using the maximum likelihood estimate ( MLE ), or a Moments expansion, which allows one to express the hyperparameters in terms of the empirical mean and variance.

For the rest of this article, sketching will be taken to mean approximate sketching.

To sample a path following this distribution from time 0 to T, we chop the time interval into M units of length, and approximate the Brownian motion over the interval by a single normal variable of mean 0 and variance.

Lyman Clothier was the man who purchased from Mr. Byce for " a yoke of oxen and a fusee " which in today's terms would mean a pair of oxen and a flintlock rifle ( approximate cost at that time was $ 14. 00 ).

In the gas phase, is often defined as the diffusional mean free path, by assuming a simple approximate relation is exact:

This approximate equation becomes exact when used to define the diffusional mean free path.

Using the central limit theorem to justify approximating the sample mean with a normal distribution yields an approximate 95 % confidence interval of the form

Penetration in vacuum is dictated by mean free path, a measure of the probability of collision between electrons and matter, approximate values for which can be derived from Poisson statistics.