cdf — Evaluate a fitted or named probability distribution cumulative distribution function.

cdf(pd,x) evaluates the cumulative distribution function for a ProbabilityDistribution object returned by fitdist. cdf(distname,x,params...) evaluates supported named distributions directly.

Syntax

p = cdf(pd, x)
p = cdf(distname, x, params)

Inputs

NameTypeRequiredDefaultDescription
pdAnyYesProbabilityDistribution object returned by fitdist.
xNumericArrayYesSample data or evaluation points.
distnameStringScalarYesDistribution name.
NameValueAnyVariadicName-value options.

Returns

NameTypeDescription
yNumericArrayDistribution function values.

Errors

IdentifierWhenMessage
RunMat:fitdist:InvalidArgumentSample data, distribution name, options, or evaluation inputs are malformed.fitdist: invalid argument
RunMat:fitdist:NumericalDistribution parameter estimation fails to converge or is ill-conditioned.fitdist: numerical failure
RunMat:fitdist:InternalRunMat cannot construct distribution outputs.fitdist: internal error

How cdf works

  • pd must be a fitted distribution object returned by fitdist, or distname must name a supported distribution.
  • Supported named distributions are "Normal", "Exponential", "Lognormal", "Gamma", "Weibull", and "Poisson" with their standard scalar parameters.
  • x may be a scalar or numeric array; the output has the same shape as x.
  • Supported fitted distributions are normal, exponential, lognormal, gamma, Weibull, and Poisson.

Examples

Evaluate a fitted normal CDF

pd = fitdist([1;2;3], "Normal"); p = cdf(pd, 2)

Evaluate a named Poisson CDF

p = cdf("Poisson", 2, 3)

Using cdf with coding agents

Open a RunMat example with live inputs, then ask the agent to explain how cdf changes the result.

Run a small cdf example, explain the result, then change one input and compare the output.

FAQ

How do I compute inverse probabilities?

Use icdf(pd,p) with the fitted distribution object.

Open-source implementation

Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how cdf is executed, line by line, in Rust.

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