Error: index exceed matrix dimension!

Can someone help me that why i am getting error when I try to extract FRF graph from transfer_from_modes.m file.

Values that I am considering are below:

In rectangular_plate_fea.m : Length = 19.7, width = 19.7, thickness = 0.197. damping 0.000999. nodes along x and y are 20,20. First 10 frequencies extraction. boundary conditions = cantilevered thin plate

In transfer_from_modes.m : stiffness/mass, force/displacement options and homogeneous plate.

mass and stiffness matrix are same that I got from rectangular_plate_fea.m file. I consider frequency step 25 , minf= 100, maxf=200.

My problem Is when I enter 1200 dof for response and 609 for excitation I get error of Index exceed matrix dimensions. why I am getting this either where i am making mistake In whole analysis.What should I consider if I am applying a concentrated force somewhere in the middle of plate at a specific node?

.m files are attached with there supporting functions.

[Walter Roberson]

It would help to know the correct sequence of input values, in order. Plate type? Material? uniform nonstructural mass? inputs to specify mass??

[zainab malik]

In rectangular_plate_fea.m

Length 19.7

width 19.7

nodes along x 20

nodes along y 20

plate type = homogeneous

thickness = 0.197

material = aluminium

non structural mass = no

Boundary condition = other (bottom edge free, right edge free, top edge free, and left edge fixed)

First n eigen values

10 vectors

iterations 2 In transfer_from_mode.m

Input method = mass/stiffness

output = displacement/force

units = inch

mass matrix name = mass

divide by 386 = no

stiffness matrix name = stiff

damping input = constant for all

damping ratio = 0.000999

mode no of interest 6

frequency step = 25

maxf = 300

minf = 200

dof pair input method = manual

diplasy plots yess

fig_num 1

response = 1200

excitation 609

[zainab malik]

Onward frequency step you may choose any values according to above analysis. Help me resolve this error kindly

Answer 1

[Walter Roberson]

You have 20 x 20 = 400 nodes, and if unconstrained there would be 3 dof per node, for a total of 1200, matching the 1200 you select for response.

However, you are not unconstrained: your "other" constraint fixing the left edge is reducing your dof from 1200 to 1104, so the calculations are on 1104 x 1104 matrices and you are trying to ask for the 1200'th of those.

[zainab malik]

Yes you are right thank u. But now which matrix should I call for, or I should enter manually 1104. am still getting

Error:

Error using save Unable to write file H_disp_force_1140_609.txt: permission denied.

Error in transfer_from_modes_H_files (line 57) save(v1,'str1','-ASCII');

Error in transfer_from_modes (line 255) [varname1,varname2,varname3]=transfer_from_modes_H_files(iam,i,k,freq,H,HM);

[Walter Roberson]

You should manually enter 1104 (I guess.)

You should be running your code from a directory that you have write access to.

[zainab malik]

Sir @Walter Roberson thank you so much! Its working now.