International Business Machines Corp., the world's largest computer maker, yesterday said first-quarter earnings were up 5.3 per cent over last year's first-quarter results.

Chairman Frank T. Cary said earnings from worldwide operations were $573 million ($3.82 a share) compared with $544 million ($3.63).

Cary noted that outright purchases of data processing equipment, although somewhat higher than during the first quarter of 1976, were substantially less than the record purchase volume experienced in the final quarter 1976.

First-quarter sales of all products rose by 6.8 per cent to $1.37 billion from $1.29 billion the year before, but were more than 25 per cent, below the $1.84 billion recorded in the fourth quarter of 1976.

Gross income was $4.09 billion compared with rentals and services increased by 7.5 per cent over the first quarter of 1976.

Cary said "demand for the company's products is strong, reflecting the continuing improvement in economic conditions in most of our major marketing areas around the world."

Westinghouse Electric Corp. yesterday said its first-quarter net income increased about 12.5 per cent over the same period last year to a first period record despite a slight drop in sales.

Chairman Robert E. Kirby said income for the first three months was $53.2 million (61 cents a share) compared with $47.2 million (54 cents). Sales for the quarter were $1.43 billion compared with $1.44 billion for the same period last year.

The 1976 figure included the sales of a Belgian subsidiary, which was not included in the 1977 figure because Westinghouse has become a minority owner. Excluding the Belgian firms's sales, the Westinghouse 1977 first-quarter sales increased by 7.3 per cent over last year, Kirby said adding that the effect on earnings was negligible.

The first-quarter results included the effect of a settlement of a uranium suit involving three utilities, which Westinghouse estimates will cost the company 6 million.

The utilites will get $5 million in cash as well as equipment, discounts and technical advice. The utilities say the total value of the package to them is about $15 million.

Kirby said the latest income figures "reflect the progress we have made over the past two years to improve profit margins."

J.P. Morgn & Co., a bank holding company, had a 10.4 per cent gain in first-quarter operating profit and an 11.1 per cent rise in net income to $50.4 million ($1.24 a share) from $45.23 million ($1.16) on 2 million fewer shares a year ago.

Stockholders equity increased by $134 million from a year earlier. Net interest earnings of Morgan Guaranty Trust Co. rose to $160.2 million from $156.8 million, but average interest return to the bank fell to 7.56 per cent from 8.06 per cent a year ago.

The provision for possible loan losses in the quarter was $12.9 million, down from $20.4 million in the 1976 first quarter, and net loan charge-offs dropped to $12.3 million from $17.7 million a year earlier.

Raytheon Corp. yesterday reported a 27 per cent gain in first-quarter earnings to $1.50 a share from $1.18 a year ago. Net income was up 29 per cent to $23.04 million on sales of $661.59 million compared with $17.9 million a year ago on sales of $572.41 million.

The gains reflected strong performing government systems and commercial electronics orders, the company said.

General Dynamics Corp. yesterday said its profits in the first quarter increased to $18.79 million ($1.73 a share) from $17.24 million ($1.59) a year earlier. Sales in the first three months rose to $678.44 million from $568.37 million.

Addressing shareholders attending the company's annual meeting in St. Louis, chairman David S. Lewis said General Dynamics' order backlog of $6.5 billion was the highest in company history and that it includes only $300 million so far from F-16 fighter program.

Caterpillar Tractor yesterday said its first-quarter net income fell to $98 million ($1.11 a share fully diluted) from $101.3 million ($1.15) a year earlier, as sales grew from $1.199 billion to $1.363 billion.

The company is the 29th largest industrial corporation in terms of 1975 sales, according to Fortune magazine's yearly listing of major businesses. It manufactures earth-moving, construction and materials-handling equipment, and diesel and natural gas engines.

Decreased production resulting from gas curtailment during athe cold weather and a strike at its Tennessee plant reduced first-quarter earnings of Owens-Corning Fiberglas Corp. despite an increase in sales.

However, President William W. Boeschenstein, said the severe winter weather and tax incentives for better home insulation beign considered by Congress should strengthen the firm's fiberglass insulation market considerably in the coming year.

Earnings for the first three months of 1977 were $15.4 million ($1.02 a share) compared with $16.0 million ($1.08) during the same period in 1976. Sales for the quarter were $276.8 million, up from $252.4 million the year before.

Celanese Corp., one of the country's largest producers of man-made fibers, yesterday reported a sharp decline in first-quarter earnings.

The company said net income was $11 (74 cents a share) compared with $24 million ($1.67) a year earlier. Sales fell from $562 million to $546 million.

President John D. Macomber, said the lower earnings reflected a continuation of the low level of earnings reported during the last half of 1976.

Control Data Corp. had a 10 per cent increas in earnings for the first quarter ended March 31 compared with the same quarter a year ago, the company reported yesterday.

Consolidated net earnings were $11.7 million (67 per cent a commom share) compared with $10.2 million (58 cents) a year ago.

Board chairman William G. Norris said the gains resulted from a strong performance of all major segments of Control Data's comuter business. However, he added that the gains were paritally offset by lower net earnings in financial servicesresulted of adverse foreign currency exchange rates.