How can I use the numeric value of a Physic variable

Im working in a code that works with physycal variables and I need to operate with a physical variable and this function:

7.537326681679638e-004 * exp (0.921 * u) * u

where "u" represents the physican variable.

The physical variables are defined like this Argument 1 = {[1x1 double], 'V'}", so there is a numeric value and its unit, in this example, V ( volts)

When i try to run it, the program complains as follows:

"No matching signature found for exp. exp takes one dimensionless argument.

Argument 1 = {[1x1 double], 'V'}"

I cant find a way to use just the numeric value of the argument. Is there any way to do it?

[TADA]

Try this:

uv = {1};
7.537326681679638e-004 * exp (0.921 * uv) * uv

[manel cugota]

It doesn't work, it say's:

Illegal use of cell array syntax in declarative construct. Only unit expressions {expression, 'character vector'} may use the '{}' syntax in declarative constructs.

[Jan]

"It says ..." and "when i try to run it" is not useful. Please post the rlevant part of the code and a copy of the complete error message.

There are no "physical variables" in programming languages and you cannot expect the standard operators of Matlab to handle your cell arrays as you expect it.

Answer 1

[Jan]

You can find some toolboxes and functions for handling physical units in the FileExchange: https://www.mathworks.com/matlabcentral/fileexchange?q=physical+unit

• https://www.mathworks.com/matlabcentral/fileexchange/38977-physical-units-toolbox
• https://www.mathworks.com/matlabcentral/fileexchange/23908-fundamental-physical-constants-and-unit-conversion-in-si-mks-gaussian-cgs-units
• https://www.mathworks.com/matlabcentral/fileexchange/69125-physicalquantity
• https://www.mathworks.com/matlabcentral/fileexchange/40633-working-with-physical-properties-and-units-in-matlab
• ...

[manel cugota]

Finaly i could do it using the function value()

parameters

p = {1,'m'}

end

parameters(Access = private)

pd = my_fcn(value(p,'m')); % extract unitless value from p

end

Thanks for the help.