c++ - Indexing into CHOLMOD dense vector array -


i have cholmod_dense data structure:

cholmod_dense* ex = cholmod_l_solve(cholmod_a, l, b, &com);

and want extract values , copy them variable. means need index double array , copy values over.

for (int k=0; k<ncols; k++) t_x[k]=((double*)ex->x)[k];

which compiler ok segmenation fault. or think should able do:

double* e_x =(double*)ex->x; (int k=0; k<ncols; k++) t_x[k]=*e_x[k];

but compiler dislikes this:

error: invalid type argument of unary ‘*’ (have ‘double’) (int k=0; k<ncols; k++) t_x[k]= *e_x[k];

according cholmod userguide:

  1. cholmod dense: dense matrix, either real, complex or zomplex, in column-major order. differs row-major convention used in c. dense matrix x contains • x->x, double array of size x->nzmax or twice complex case. • x->z, double array of size x->nzmax if x zomplex.

so should able grab ex->x , index double array, cannot without getting segmentation fault. can me out?

the cholmod library written in c , code linking cholmod library (the code snippet shown above) c++.

ok, looks likes made couple mistakes.

first of all, running segmentation fault because using cholmod_l_zeros(); assumes long integers. instead, should using cholmod_zeros(); since using doubles.

after fixing ran error cholmod error: invalid xtype right after cholmod_solve(cholmod_a, l, b, &com); statement. because cholmod_factor* l defined out of scope. after fixing both of these issues, code copies values cholmod_dense ex->x double array on t_x double vector:

cholmod_dense* ex = cholmod_solve(cholmod_a, l, b, &com); double* e_x = (double*)ex->x; (int k=0; k<ncols; k++) t_x[k] = e_x[k];

i unaware [] operator automatically dereferences pointers. know!


Comments

Post a Comment

Popular posts from this blog

php - Vagrant up error - Uncaught Reflection Exception: Class DOMDocument does not exist -

i've set bento/ubuntu-16.04 vagrant box using php 5.6, , getting following error quite few times when try , run shell script: "uncaught reflection exception: class domdocument not exist". i've tried adding following top of script (not together), each no success: "sudo apt-get install php5.6-xml", "sudo apt-get install php5-xml", "sudo apt-get install php-dom" i've tried resetting server "sudo service apache2 restart". does have suggestions?
Read more

vue.js - Create hooks for automated testing -

Image
qa guys complained can't automate frontend testing. because our html looks same outside. lazy hack did this <template> <div :role="$options.name"> ... </div> </template> <script> export default { name: 'vmcomponentname' } </script> which takes name script , applies html. in browser get: <div role="vmcomponentname"> ... </div> line :role="$options.name" goes in every component. is there dry er solutions? please share. additional details i'll explain in details looking for. imagine have vmusercreate form creates user. test case can create user . to automatically test without role, have use following selector: .wrapper > .wrapper > .wrapper > .submit-button the test extremely brittle (will break lot). if use roles can use [role="vmusercreateform"] .submit-button selector. many folds less brittle. so basically, i'm ...
Read more

Add new key value to json node in java -

i have json file : { "id":1, "name":"abc", "addressdetails": { "city":"newyork" } } i wanted add 1 more key-value ("pincode" : "414141") node 'addressdetails'. i tried using : objectmapper mapper = new objectmapper(); jsonnode root = mapper.readtree(new file("d://test.json")); objectnode node = mapper.createobjectnode(); node.with("addressdetails").put("pincode", "414141"); but it's not getting added, there way can ? you can try you should modify file path objectmapper mapper = new objectmapper(); objectnode nodes = mapper.readvalue(new file("d:\\test.txt"), objectnode.class); nodes.with("addressdetails").put("pincode", "414141"); mapper.writer().writevalue(new file("d:\\test.txt"), nodes);
Read more