# Error Messages/40548

## Error text

Too many parameters have been provided to Function LogNormal. You should specify only two of the parameters median, gsdev, mean, and stddev. For example, LogNormal(median: 5, stddev: 3) or LogNormal(mean: 5, gsdev: 3).

## Cause

The LogNormal function has 4 parameters that can be used to specify the parameters of the log normal distribution, but you must specify only 2 of these when you use it. The 4 parameters are there because you may find it more convenient is different situations to specify the distribution with different combinations of the four parameters.

In general, any two of the parameters uniquely specifies the LogNormal. Another way of saying this is that if you know two of the parameters (median, mean, stddev or gsdev), you could figure out what the other two must be.

Analytica doesn't require you to use the named-parameter calling convention -- you can specify the parameters either positionally or by name. However, in the case of LogNormal, we strongly prefer using a strict named-parameter calling convention, such as:

`LogNormal(mean: 5, stddev: 3)`

rather than the equivalent positional notation:

`LogNormal(, , 5, 3)`

When you need to read the definition later, you can see that the named-parameter convention is much clearer.

## Remedy

Remove one or more of the parameters so that only two are specified.

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