Help using rowfun?

I'm trying to use rowfun on an 18x2 table created here:

            peaks= table(rot90(locs,3),pks,'VariableNames',{'d' 'int'});

I'm trying to apply the following function (titled intovol) after defining lambda and energy earlier in the script

function [ phase, chemeq, volume ] = intovol(lambda,energy,d,int)

using rowfun:

            volumes = rowfun(intovol(lambda,energy,d,int),peaks);

Together in the script they look like this:

              peaks= table(rot90(locs,3),pks,'VariableNames',{'d' 'int'});
              volumes = rowfun(intovol(lambda,energy,d,int),peaks);

But I keep getting the error "Undefined function or variable 'd'."

How do I get row fun to assign the values of the first and second columns of the table to variables in the function? I've tried using

volumes = rowfun(intovol(lambda,energy,d,int),peaks,'InputVariables',{'d' 'int'})

but it didn't work

Answer 1

[Steven Lord]

The ROWFUN function requires as its first input a function handle to a function to be executed for each row in the table. See how all the examples on that page pass function handles (which could be an anonymous function) in as the first input? You're not passing a function handle as the first input in your call; you're instead calling a function and passing whatever it returns as the first input. This could work if what you're calling returned a function handle, but it refers to a variable that doesn't exist.

Read through the examples on that page of how to specify a function handle and how to tell ROWFUN which variables in the table are inputs and which control how the rows are grouped.

[Brooke Sarley]

I used the function handle originally, but that doesnt allow me to call lambda and energy into the equation. I thought about adding two columns of values to the table I'm running through rowfun in order to able to use those variables.

However, I don't know how to add a column of values of one value. I'm working on that right now. This way lambda and energy act as constants for every iteration of the function for each row

[Stephen23]

@Brooke Sarley: you can create another function handle based on the first one, that specifies the values of lambda and energy:

@(d,i)intovol(lambda,energy,d,i)

See the documentation on anonymous functions.

[Brooke Sarley]

Thank you Stephen. I'd accept the answer but you answered it, not Steven.