Raul and Eric, thanks for your responses. I realize there was still room for improvement in my example. I failed to include the line
x=.1200$<a. showing what the value of x was before the first instance of 7!:5 x My point was that the space required by x depended on how its value (in all cases equivalent to 1200$<a.) was constructed, even before assignment to the name 'x'. So if I use 7!:5 to try and estimate the size required for a mapped file, I could come out wrong and (later) get an allocation error. As for the problem with createjmf_jmf_, the earlier lines in my application just created a large variable from an even larger .csv text file. The large variable was a boxed table of five columns, the first three containing character strings and the last two containing integers. I then measured the size sz of this table using 7!:5, constructed a filename fn, and created a jmf file using createjmf_jmf_ fn;sz. I get the message |bad jmf header: assert | 'bad jmf header' assert 0[free fh,mh,fad . While writing this reply I was running the program again with debugging enabled, and it stopped at the same spot, so I shall do some checking while I can get at the local variables. But I expect things to be the same as before: if I try to map any variable to the jmf file (which was indeed created) I shall get the same error. But if I recreate the file manually and map a variable to it, it will work. It is important to me that it work under program control and not require manual intervention. Dick V. This message is intended only for the addressee and may contain information that is confidential or privileged. Unauthorized use is strictly prohibited and may be unlawful. If you are not the intended recipient, or the person responsible for delivering to the intended recipient, you should not read, copy, disclose or otherwise use this message, except for the purpose of delivery to the addressee. If you have received this email in error, please delete and advise the IT Security department at [EMAIL PROTECTED] immediately. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
